# Evaluation of the Potential Impact

of Emissions of HFC-134a From Non Professional Servicing of Motor Vehicle Air Conditioning Systems

CARB Agreement No. 06-341

Prepared for



### State of California Air Resources Board

Research Division
PO Box 2815 Sacramento, CA 95812

Final Report

Arnaud TREMOULET, Youssef RIACHI, David SOUSA, Lion el PALANDRE, Denis CLODIC and the participation of
Aline GARNIER for documentation Simon CLODIC and Martin LANSARD for surveys in Cali fornia

December 2008

## DISCLAIMER

The statements and conclusions in this Report are t hose of the CEP-Armines and not necessarily those of the California Air Resources B oard (ARB). The mention of commercial products, their source, or their use in connection with material reported herein is not to be construed as actual or implied endorsement of such products.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 

## Contents

Abstract...........................................

................................................... ................................................... .........1 Executive summary ..................................

................................................... ..................................................2
Introduction.......................................

................................................... ................................................... .......5 1. Measurements of initial leak flow rate (LFR) of the five most used MAC systems in California ....... ........5
1.1 Test method ....................................

................................................... .................................................5
1.2 Tests results..................................

................................................... ................................................... 6 1.2.1 MAC system A .................................

................................................... .........................................6 1.2.2 MAC system B .................................

................................................... .......................................10
1.2.3 MAC system C.......................................

................................................... .................................12 1.2.4 MAC system D.................................

................................................... .......................................14
1.2.5 MAC system E .......................................

................................................... .................................16
1.3 Conclusion.........................................

................................................... .............................................18 Appendix 1: Leak flow rate and mole number graph MA C system A......................................... .................20 Appendix 2: Leak flow rate and mole number graph MA C system B......................................... .................21 Appendix 3: Leak flow rate and mole number graph MA C system C......................................... .................22 Appendix 4: Leak flow rate and mole number graph MA C system D......................................... .................23 Appendix 5: Leak flow rate and mole number graph MA C system E......................................... .................24 2. Analysis of current recharge by non professional s in California .................................... .........................25
2.1 Introduction...................................

................................................... ..................................................2 5 2.2 Small cans: description and leak test results..

................................................... ...............................25 2.2.1 Small can description........................

................................................... ......................................25 2.3 Analysis of recharge by do-it-yourselfers (DIYe rs)................................................ ................................26 2.3.1 Operating procedure for emission assessment ..

................................................... ........................27 2.3.2 Descriptions of the small can user sample ....

................................................... .............................27 2.3.3 Vehicle analysis .............................

................................................... .............................................29 2.3.4 Charging procedure evaluation................

................................................... ...................................30 2.3.5 Refrigerant emissions associated with the use of small cans..................................... ...................36 3. Analysis of current leak search and recharge by professional servicing in California ............... .............40
3.1 Introduction...................................

................................................... ..................................................4 0 3.2 Operating procedure to perform professional ser vicing analysis.................................... ..................41
3.2.1 Simulation of AC failure .....................

................................................... .....................................41 3.2.2 Description of the MACS used................

................................................... ...............................41 3.2.3 Selection of professional garages and sample description ....................................... ...............43 3.3 Analysis of current leak search and recharge by professional servicing ............................ ..............44 3.3.1 Preliminary AC check by professional servic ing................................................ ......................44 3.3.2 Leak search and recharge by professional se rvicing ............................................ ..................45 4. Laboratory Testing..............................

................................................... ..................................................5 2 4.1 Evaluation of potential leak sources of profess ional servicing.................................... ......................52 4.1.1 System performances related to refrigerant ch arge ............................................... ...................52 4.1.2 Potential leak sources during a typical maint enance procedure ................................... ............54 4.1.3 Recommended service procedure................

................................................... ..........................57 4.2 Leak tightness tests of brand new and after use small cans ........................................ ....................58
4.2.1 Introduction .................................

................................................... ............................................58 4.2.2 Description of small cans....................

................................................... ....................................58
4.2.3 Tests and results............................

................................................... .........................................63
4.2.4 Conclusions .................................

................................................... ..........................................66 4.3 Sensitivity of different leak search methods...

................................................... ................................67
4.3.1 Introduction .................................

................................................... ............................................67 4.3.2 Test procedure...............................

................................................... .........................................67
4.3.3 Leak test results and conclusions............

................................................... ...............................68 5. Evaluation of the sales of HFC-134a disposable c ans in California .................................. .....................71 6. Summary, conclusions, and recommendations.......

................................................... .............................72
References .........................................

................................................... ................................................... ...77 Abbreviations and acronyms .........................

................................................... ...........................................77
AnnexesEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 1 - 

### Abstract

This project included laboratory testing and field studies to evaluate the methods and procedures used by both professionals and non-profe ssionals while servicing mobile airconditioning (MAC) systems. A majority of professi onal technicians used recovery and recharge machines with some using small cans. All non-profe ssional do-it-yourself (DIY) individuals used small cans. Field testing was also conducted to de termine refrigerant emissions from nonprofessional servicing. While the data indicated t hat the majority of the refrigerant was charged into the MAC systems, thirty-three percent was emit ted to the atmosphere. Laboratory testing was performed to measure the leak rate from small c ans and charging hoses and to compare different leak detection techniques used by profess ional technicians. In addition, testing was
conducted to measure the initial leak flow rate of new MAC systems installed in the 5 most popular vehicles in California.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 2 - 

### Executive summary

Background

This research project will assist ARB in the mitiga tion of Climate Change as required in the California Global Warming Solutions Act. Specifica lly, the results of this study will assist in the development of a regulatory measure reducing the em issions of high global warming potential (GWP) refrigerants used by non-professional individ uals in re-charging their motor vehicles’ air conditioning (MVAC) systems. ARB is interested in gaining an understanding of the nature of non-professional MVAC servicing and the resulting e missions of high-GWP refrigerant. In addition, ARB wants to evaluate professional servic ing of MVAC systems in order to understand its advantages in comparison to non-professional se rvicing. The data and information from this project could be beneficial for the development oth er potential measures concerning high-GWP refrigerants used in MVAC systems, emission reducti ons from leaking MVACs, and professional servicing.

Method

This research project consisted of two parts. In o ne part, ARMINES’ Center for Energy and Processes (CEP) staff conducted field testing and f ield evaluations of non-professional DIY MVAC servicing and a field survey and evaluation of professional MVAC servicing. The rest of the project included the laboratory testing of diff erent MAC systems, DIY containers and charging hoses, and different leak detection techni ques used by professional technicians.

The field testing included the measurement of the r efrigerant emissions from non-professionals performing MAC servicing using “small cans.” Refri gerant emissions were determined by taking a mass balance approach where an individual perform ed a “small can” re-charge on a MVAC system containing a known quantity of refrigerant. This is followed by weighing the container to determine the remaining refrigerant and refrigerant recovery from the MVAC system in order to determine how much refrigerant was charged into the system by the non-professional. In addition, the individuals performing the DIY practi ce were profiled and the procedures used during the MVAC re-charging were characterized and evaluated. This latter qualitative approach was also used with professional technicians who wer e asked to diagnose and perform corrective actions on an undercharged MAC system provided in a CEP vehicle. The professionals’ diagnoses and servicing recommendations were compil ed and evaluated.

The laboratory testing was conducted at the CEP fac ility and included the measurement of the performance of a single MVAC system which was mount ed on a test bench. During the test, system parameters, including evaporator air tempera ture, were measured to observe how the cooling performance decreased as the refrigerant ch arge was reduced.

CEP staff also measured the leak rates of automotiv e refrigerant containers and the hose
assemblies before and after container valve actuati on. The containers and container/hose assemblies were placed inside an accumulation volum e and an infrared spectrophotometer was used to measure the rise in refrigerant concentrati on inside the volume over time. Testing was also conducted to compare the sensitivity of differ ent leak search methods using a leak detector, ultraviolet dye with a lamp, and soap/water solutio n on a pressurized MVAC system joints. In addition, CEP staff measured the annual leak flow r ates (LFRs) of the MAC systems on the five most sold cars in California in a laboratory. The laboratory testing was performed in mini-sheds (small chambers) at the CEP facility. All of these leak tests were performed using a methodology specified in the European Regulation 70 6/2007.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 3 - 

### Results

Non-professional Servicing In general, it was observed that DIY individuals re charge their MVAC systems without knowing the amount of refrigerant remaining in the MVAC sys tem, the manufacturers’ specified refrigerant charge, and without making a diagnosis of any problems including a search for leaks. Moreover, instructions on the container’s label giv e incorrect information about re-charging the air conditioning system. Results from the field te sting of the non-professionals indicate that twothirds of the refrigerant in the small can is charg ed into the MAC system with the remainder released to the atmosphere. Refrigerant emissions from the DIY procedure is split with two thirds remaining in the container (can heel) which is eventually breached releasing the contents to the atmosphere. One third is released to the at mosphere during recharging. Based on a field survey, the typical cost of a can plus the rechargi ng kit varies from $15 to $ 40.

Professional Servicing One of the benefits of professionals servicing is t he diagnosis of problems with MVAC operation along with the servicing or repair. Most professio nal technicians measure the air temperature coming from the vents in the cabin, check the compr essor clutch actuation, and measure the high and low pressures of the system. The vast maj ority of the technicians recommend the use of ultraviolet-sensitive dye with a UV lamp to dete ct leaks. Some use electronic detectors. All of
these methods have detection limits below which the se methods will not work. The majority of professional repair and servicing facilities use au tomated recovery and recharge machines which minimize refrigerant emissions during servici ng. The cost of professional servicing ranges from $80 to $200 for diagnosis, recovery and rechar ge with a machine, and, depending on the shop, includes a leak search. This estimate does n ot include the more costly repairs such as replacing a compressor.

Laboratory Testing Testing in the lab allowed CEP staff to collect dat a for MVAC systems and components under situations that we would not have been possible in the field. The results of the collection of MVAC performance data versus decreasing refrigerant charge indicated that there is no significant deterioration in the cooling performanc e until the refrigerant was reduced to approximately half of manufacturer’s specified char ge.

Testing was also conducted to compare three leak de tection methods which included the use of an electronic leak detector, the detection of soap bubbles on a MVAC system pressurized with
CO 2 

### or air, and the injection of UV-sensitive dye into a system with the use of a UV lamp to detect leaks. Data from the testing indicates that the usage of UV dye is capable of detecting a leak of 6 g/yr with an 11 hour waiting period. Thi s is as sensitive as an electronic leak detector and more sensitive than the soap bubble detection m ethod.

For the leak rate measurement of small containers, there is no significant emission difference between the screw-and-perforate (S&P) and valve-equ ipped cans prior to usage. However, when considering a used container the leak rates fo r the "push-button" type charging kits on the S&P containers were very significant when compared to the valve-equipped cans or the S&P
containers with the shut-off valve installed.

The average annual LFR of the five most sold MAC sy stems in California is 10±4 grams per year which indicates that U.S. MVAC systems are comparable to the European and Japanese systems in terms of leakage.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 4 - 

### Conclusions

There are significant differences between professio nal and non-professional servicing operations. The use of small cans by non-professio nals results in emissions of about 1/3 of the refrigerant contained in small cans. It is possibl e that “small can” usage by professionals may result in lower emissions. The most significant ad vantage of professional servicing, in terms of emissions, is the use of an automated R&R machine w hich results in re-charging emissions that may be lower than 5 g per operation. This compares favorably to refrigerant emissions of more than 110 g per servicing when non-professionals use small cans.

The initial leak tightness of U.S.-made MAC systems is in the neighborhood of 10 grams per year. If this leak tightness were to be maintained over a lifetime, no recharge should be necessary for 15 years. However, HFC-134a sales in dicate that the leak flow rates of MAC systems increase with time with many MVACs requirin g service after 6 to 8 years of operation.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 5 - 

### Introduction

The main objective of this research project was to develop experimental data in order to better estimate emissions of HFC-134a due to non-professio nal servicing of MAC systems. The overall study design was divided into six tasks and are presented as follows:

 

### Measurements of initial leak flow rate (LFR) of the five most used MAC systems in
California

 

### Analysis of current recharge by non-professionals i n California

 

### Analysis of current leak search and recharge by pro fessional servicing in California

 

### Laboratory tests simulating non-professional operat ing modes in California

 

### Evaluation of the sales of HFC-134a disposable cans in California

 

### Recovery of samples of disposable cans after usage by non-professionals in California



### 1. Measurements of initial leak flow rate (LFR) of the five most used MAC systems
in California

1.1 Test method

The test bench dedicated to the leak flow rate meas urement of the whole AC system has been developed by CEP [ACE05]. The leak measurements ar e performed in accordance with the European directive 2006/40/EG [EUD06]. The test pr ocedure detailed by the European regulation 706/2007 [EUR07] is described below.

The MAC system (see Photo 1.1) is first mounted, ev acuated and charged with the nominal manufacturer refrigerant charge ( ± 1 gram) and then installed inside the mini-shed.

According to the specifications given by EUR07, the pre-conditioning is performed at 50°C for 10 days. Thereafter, the mini-shed is rinsed and test s are carried out at 40°C. In order to establish a regression correlation on the five U.S. MAC syste ms, three temperatures are successively controlled in order to measure the three correspond ing leak flow rates (LFR).

Photo 1.1: Installation of MAC system in mini-shed.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 6 - 

### An infrared photo-acoustic spectroscope, having a d etection limit of 15 ppb, measures the refrigerant accumulated inside the mini-shed. The mass flow rate is the product of the molar
mass and the derivative of the number of moles of H FC-134a with respect to time in the test chamber volume (the test chamber). The perfect gas law is used to take into account the small variations of pressure and temperature inside the t est chamber. According to Equation (1.2), the following parameters need to be determined for leak flow rate calculation: the accumulation

volume of the test chamber

accum 

### V , the temperature amb 

### T and the pressure amb



### P inside the test

chamber, and the evolution of concentration with ti me.

The method used to determine the leak flow rate (LF R) is based on Equation (1.1).



## t n M m a HFC

a HFC a HFC 

## ∂

∂

⋅ = −

− − 134

134 134 

## & Equation(1.1)

Where,



### C T R V P C n n

amb accum amb

total a HFC 

### ⋅

⋅ ⋅

= ⋅ =

− 134 

### Equation(1.2)

HFC-134a mass flow rate (g.s -1 

### )

HFC-134a molar mass (102 g.mol -1 

### )

Number of mole (mol)

t Time (s)

C Refrigerant concentration (ppm)

Ambient pressure (Pa)

Accumulation volume (m 3 

### )

Gas constant (8.314x10 3 

### kJ kmol -1 

### K -1 

### )

Ambient temperature (K)



### 1.2 Tests results

All five MAC systems were purchased from each manuf acturer and mounted in the CEP test chambers according to manufacturers specifications and instructions.



### 1.2.1 MAC system A

System specifications

Table 1.1 System specifications.



### Reference System A Type SUV
Motorization / Vintage 2002-2004 MAC system Dual evaporator Nominal refrigerant charge 1400 gEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 7 - 

### System design

Photo 1.2 Assembled MAC system A.

Table 1.2: List of components.



### Components Numbers of

components Comments

Compressor 1
Condenser 1 LP receiver 1 Located on the outlet of the evaporat or 1 Evaporator 2 Expansion valve 2 Evaporator 1: Orifice tube Evaporator 2: TxV Liquid line 3
Suction line 2 HP service valve 1 Located on the discharge line LP service valve 2 Located on the liquid line 1 & 2 HP sensor 1 Located on the discharge line
LP sensor 1 Located on the LP receiver Condenser Condenser

Compressor

Evaporator 1

E

v LP receiver Services valvesEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 8 - 

### Leak flow rate calculation

Table 1.3 summarizes the MAC system A leak flow rat es for 3 different temperatures.

Figure 1.1 illustrates the leak flow rate as a func tion of pressure.

Table 1.3: LFRs of MAC system A.

T(°C) Saturation Pressure (kPa) LFR (g/yr)

30 770 13.0 ± 0.8

40 1017 25.3 ± 1.5

50 13118 44.8 ± 2.7

0 10 20 30 40 50 60

0 200 400 600 800 1000 1200 1400 1600LFR(g/yr)

Pressure(kPa) MAC system A

Figure 1.1 LFRs & Regression curve.



### Using the method of least squares, a good relations hip between the measured values and the regression curve of the binomial expression has bee n verified and is expressed by Equation 1.3.



### ) ( 2 2

downstream upstream 

### P P k LFR

− = Equation(1.3)

The objective of this approximation is to find a ge neral approach for MAC system leakage behavior as a function of pressure, which will be u sed for leak flow rate prediction at a required temperature. Once the equation parameter K is dete rmined, the MAC leak flow rate is then calculated at the corresponding temperature for eac h zone.

Considering the population for 10 California zones, the LFR is determined as a function of the temperature for the saturation pressure and then re lated to the population.

Example: taking the Arcata zone (see Table 5), a me an temperature of 10.4°C corresponds to the saturation pressure of 420 kPa. Using Equation 1.3, a leak flow rate value of 4.2 g/yr (2.536x10 -5 

### *(420 2 

### -101 2 

### )) is obtained.

Table 1.4 Determination of the annual LFR of MAC sy stem A taking into account CA population.

Arcata Bakersf

ield Daggett Fresno Long

Beach Los
Angeles Sacramento San
Diego San

Francisco Santa

Maria Annual mean T(°C) 10.4 18.5 19.8 17.1 17.2 16.7 15.2 17.6 13 .1 12.9 Saturation Pressure(kPa) 420 546 568 522 523 516 492 530 459 456

LFR(g/yr) 4.2 7.3 7.9 6.7 6.7 6.5 5.9 6.9 5.1 5.0 Population 790525 4669274 2962948 12901515 3443421 293392 9 5966569 2173073 35841254 % Population 2.2% 13.0% 8.3% 36.0% 9.6% 8.2% 16.6% 6.1% 100%

LFR% 0.1 1.0 0.5 2.3 0.6 0.6 0.8 0.3 6.3 K= 2.536E-05 TotalEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 9 -

Figure 1.2 LFR variations taking the population int o consideration.



### Figure 1.2 shows the annual leak flow rate correspo nding to the zone temperature as well as the annual leak flow rate related to the population.

Evaporator 2 MAC System AEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 10 - 

### 1.2.2 MAC system B

System specifications

Table 1.5 System specifications.



### Brand MAC system B Type Van
Motorization 3.3 l SMPI Vintage 2005 MAC system Dual evaporator Nominal refrigerant charge 1080 g

System design

Photo 1.3 Assembled MAC system B.

Table 1.6 List of components.



### Components Numbers of

components Comments

Compressor 1
Condenser 1 HP liquid receiver 1 Located on the principal liqui d line Evaporator 2 Expansion valve 2 Thermal expansion valve Liquid line 5
Suction line 4 HP service valve 1 Located on the main liquid line
LP service valve 1 Located on the main suction line HP sensor 1 Located on the main liquid line after t he HP receiver Evaporator 1

Evaporator 2 Condenser

CompressorEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 11 - 

### Leak flow rate calculation

Table 1.7 LFRs of MAC system B.

T (°C) Saturation Pressure (kPa) LFR (g/yr)

30 770 19.6 ± 1.2

40 1017 33.0 ± 2.0

50 13118 59.4 ± 3.6

0 10 20 30 40 50 60 70

0 200 400 600 800 1000 1200 1400 1600LFR(g/yr)

Pressure(kPa) MAC system B

Figure 1.3 LFRs & Regression curve of MAC system B

.

Table 1.8 Determination of the annual LFR of MAC sy stem B taking into account CA population.

Arcata Bakersf

ield Daggett Fresno Long

Beach Los
Angeles Sacrame

nto San

Diego San

Francisc

o Santa

Maria Annual mean T(°C) 10.4 18.5 19.8 17.1 17.2 16.7 15.2 17.6 13 .1 12.9 Saturation Pressure(kPa) 420 546 568 522 523 516 492 530 459 456

LFR(g/yr) 5.6 9.7 10.6 8.9 8.9 8.7 7.8 9.2 6.8 6.7 Population 790525 4669274 2962948 12901515 3443421 293392 9 5966569 2173073 35841254 % Population 2.2% 13.0% 8.3% 36.0% 9.6% 8.2% 16.6% 6.1% 100%

LFR% 0.1 1.4 0.7 3.1 0.8 0.7 1.1 0.4 8.4 K= 3.382E-05 Total

Figure 1.4 LFR variations taking the population int o consideration. 

### MAC System BEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 12 - 

### 1.2.3 MAC system C

System specifications Table 1.9 System specifications.



### Brand MAC system C Type Pickup
Motorization 5.4 l Vintage 2007 MAC system Single evaporator Nominal refrigerant charge 940 g

System design

Photo 1.4 Assembled MAC system C.

Table 1.10 List of components.



### Components Numbers of

components Comments

Compressor 1
Condenser 1 Evaporator 1
LP receiver 1 Expansion valve 1 Orifice tube Discharge line 1 Liquid line 1
Suction line 2

HP service valve 1 Located on the discharge line

LP service valve 1 Located on the suction line
HP sensor 1 Located on the suction line

LP sensor 1 Located on the LP receiverEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 13 - 

### Leak flow rate calculation

Table 1.11 LFRs of MAC system C.

T (°C) Saturation Pressure (kPa) LFR (g/yr)

30 770 13.9 ± 0.8

40 1017 21.7 ± 1.3

50 13118 35.4 ± 2.1

0 5 10 15 20 25 30 35 40 45

0 200 400 600 800 1000 1200 1400 1600LFR(g/yr)

Pressure(kPa) MAC system C

Figure 1.5 LFRs & Regression curve of MAC system C

.

Table 1.12 Determination of the annual LFR of MAC s ystem C taking into account CA population.

Arcata Bakersf

ield Daggett Fresno Long

Beach Los
Angeles Sacramento San
Diego San

Francisco Santa

Maria Annual mean T(°C) 10.4 18.5 19.8 17.1 17.2 16.7 15.2 17.6 13 .1 12.9 Saturation Pressure(kPa) 420 546 568 522 523 516 492 530 459 456

LFR(g/yr) 3.5 6.0 6.5 5.5 5.5 5.4 4.9 5.7 4.2 4.1 Population 790525 4669274 2962948 12901515 3443421 293392 9 5966569 2173073 35841254 % Population 2.2% 13.0% 8.3% 36.0% 9.6% 8.2% 16.6% 6.1% 100%

LFR% 0.1 0.9 0.5 1.9 0.5 0.5 0.7 0.3 5.2 K= 2.093E-05 Total

Figure 1.6 LFR variations taking the population int o consideration. 

### MAC System CEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 14 - 

### 1.2.4 MAC system D

System specifications Table 1.13 System specifications.



### Brand MAC system D Type Family car
Motorization 2.4 l Vintage 2006 MAC system Single evaporator Nominal refrigerant charge 650 g

System design

Photo 1.5 Assembled MAC system D.

Table 1.14 List of components.



### Components Numbers of

components Comments

Compressor 1
Condenser 1 Evaporator 1 Expansion valve 1 Thermal expansion valve LP liquid receiver 1 Liquid line 3
Suction line 2 HP service valve 1 Located on the liquid line 2
LP service valve 1 Located on the suction line 1 HP sensor 1 Located on the liquid line 2Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 15 - 

### Leak flow rate calculation

Table 1.15 LFRs of MAC system D

. T (°C) Saturation Pressure (kPa) LFR (g/yr)

30 770 28.4 ± 1.7

40 1017 49.1 ± 2.9

50 13118 95.3 ± 5.7

0 20 40 60 80 100 120

0 200 400 600 800 1000 1200 1400 1600LFR(g/yr)

Pressure(kPa) MAC system D

Figure 1.7 LFRs & Regression curve of MAC system D

.

Table 1.16 Determination of the annual LFR of MAC s ystem D taking into account CA population.

Arcata Bakers
field Daggett Fresno Long

Beach Los

Angeles Sacramento San
Diego San Francisco Santa

Maria Annual mean T(°C) 10.4 18.5 19.8 17.1 17.2 16.7 15.2 17.6 13 .1 12.9 Saturation Pressure(kPa) 420 546 568 522 523 516 492 530 459 456 Total

K= 5.29E-05 LFR(g/yr) 8.8 15.2 16.5 13.9 13.9 13.6 12.3 14.3 10.6 10.5 Population 790525 4669274 2962948 12901515 3443421 3E+06 5 966569 2173073 35841254 % Population 2.2% 13.0% 8.3% 36.0% 9.6% 8.2% 16.6% 6.1% 100%

LFR% 0.2 2.2 1.1 4.9 1.2 1.2 1.8 0.6 13.1

Figure 1.8 LFR variation taking the population into consideration. 

### MAC System DEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 16 - 

### 1.2.5 MAC system E

System specifications Table 1.17 System specifications.



### Brand MAC system E Type Family car

Motorization - Vintage 2006 MAC system Single evaporator Nominal refrigerant charge 800 g

System design

Photo 1.6 Assembled MAC system E.

Table 1.18: List of components.



### Components Numbers of

components Comments

Compressor 1
Condenser 1 Evaporator 1 Expansion valve 1 Thermal expansion valve Liquid line 2
Suction line 2 Discharge line 1 HP service valve 1 Located on the liquid line

LP service valve 1 Located on the suction line HP sensor 1 Located on the liquid lineEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 17 - 

### Leak flow rate calculation

Table 1.19 LFRs of MAC system E.

T (°C) Saturation Pressure (kPa) LFR (g/yr)

30 770 24.2 ± 1.5

40 1017 45.3 ± 2.7

50 13118 82.3 ± 4.9

0 10 20 30 40 50 60 70 80 90 100

0 200 400 600 800 1000 1200 1400 1600LFR(g/yr)

Pressure(kPa) MAC system E

Figure 1.9 LFRs & Regression curve of MAC system E

.

Table 1.20 Determination of the annual LFR of MAC s ystem E taking into account CA population.

Arcata Bakersf

ield Daggett Fresno Long

Beach Los
Angeles Sacramento San
Diego San

Francisco Santa

Maria Annual mean T(°C) 10.4 18.5 19.8 17.1 17.2 16.7 15.2 17.6 13 .1 12.9 Saturation Pressure(kPa) 420 546 568 522 523 516 492 530 459 456

LFR(g/yr) 7.7 13.3 14.5 12.2 12.2 11.9 10.7 12.5 9.3 9.2 Population 790525 4669274 2962948 12901515 3443421 293392 9 5966569 2173073 35841254 % Population 2.2% 13.0% 8.3% 36.0% 9.6% 8.2% 16.6% 6.1% 100%

LFR% 0.2 1.9 1.0 4.3 1.0 1.0 1.5 0.6 11.5 K= 4.636E-05 Total

Figure 1.10 LFR variation taking the population int o consideration. 

### MAC System EEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 18 - 

### 1.3 Conclusion

The annual leak flow rate of a specified zone is re lated to its saturation temperature and saturation pressure as well as to the population. It is remarkable that the annual leak flow rate is more dependent on the population than temperature ( see Figures 1.11 and 1.12). With 36% of California’s population, the annual LFR in Los Ange les represents 37% of California’s LFR, even though its average annual temperature is 16°C.

Figure 1.11 Population distribution. Figure 1.12 Annual LFR distribution as a function of population and temperature zones.

System K LFR@Temp

A 2.536E-05 6.3
B 3.382E-05 8.4
C 2.093E-05 5.2
D 5.295E-05 13.1
E 4.636E-05 11.5

Figure 1.13 Vehicle annual LFR as a function of the pressure.



### Another major conclusion can be drawn: the LFRs of MAC systems mounted on the five most
sold cars in California confirm that the automotive industry is a global one, because the LFRs measured are in the same range as those measured in Europe or in Japan on MAC systems of fleet of vehicles and in laboratories: the average annual LFR of new systems is around 10 g/yr ±4 and possibly higher for some double evaporator s ystems. If this LFR were to be maintained, then MVACs would not need re-charging during the li fe of the vehicle. This is not the case due to the large quantities of refrigerant sold for the servicing of the systems. In addition, ARB performed one study (Vincent et al.) in which the d ata indicated that most MVAC servicingEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 19 - 

### occurs after 8 to 9 years of vehicle life. This st udy which included data from more than 12,500 vehicles estimated that the average LFR from MVAC s ystems is about 80 g/yr over the lifetime of the vehicles. Thus, the tightness of MVAC syste ms degrades over time probably due to a variety of factors including system operation, oper ating temperatures, and vibrations due to vehicle operation.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 20 - 

### Appendix 1: Leak flow rate and mole number graph MA C system A

• T=30°C

0 100 200 300 400 500 600

0 5 10 15 20 25 30 35 40 45 50 55 60

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q (mole)

28/03/08- System A T = 30 °C - LFR: 13.0 g/yr LFR(g/yr)

R-134a mole number



### • T=40°C

0 100 200 300 400 500 600 700 800 900 1000 1100

0 5 10 15 20 25 30 35 40 45 50 55 60

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q (mole)

31/03/08- System A T = 40 °C - LFR: 25.3 g/yr LFR(g/yr)

R-134a mole number



### • T=50°C

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

0 5 10 15 20 25 30 35 40 45 50 55 60

0 2 4 6 8 10 12 14 16 18 20 22Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q (mole)

02/04/08- System A T = 50 °C - LFR: 44.8 g/yr LFR(g/yr)

R-134a mole numberEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 21 - 

### Appendix 2: Leak flow rate and mole number graph MA C system B

• T=30°C

0 100 200 300 400 500 600 700 800

0 5 10 15 20 25 30 35 40 45 50 55 60

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

04/02/08- System B T=30 °C - LFR: 19.6 g/yr LFR(g/yr)

R-134a mole number



### • T=40°C

0 100 200 300 400 500 600 700 800 900 1000

0 5 10 15 20 25 30 35 40 45 50 55 60

0 2 4 6 8 10 12 14 16 18 20 22 24 26Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

06/02/08- System B T=40 °C - LFR: 33.0 g/yr LFR(g/yr)

R-134a mole number



### • T=50°C

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

0 5 10 15 20 25 30 35 40 45 50 55 60

0 2 4 6 8 10 12 14 16 18 20Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

07/02/08- System B T=50 °C - LFR: 59.4 g/yr LFR(g/yr)

R-134a mole numberEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 22 - 

### Appendix 3: Leak flow rate and mole number graph MA C system C

• T=30°C

0 200 400 600

0 10 20 30 40 50 60

0 2 4 6 8 10 12 14 16 18 20 22 24Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

27/04/08 - MAC system C LFR@30°C : 13.9 g/yr LFR(g/yr)

R-134a mole number



### • T=40°C

0 200 400 600 800 1000 1200

0 10 20 30 40 50 60

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

28/04/08 - MAC system C LFR@40°C : 21.7 g/yr LFR(g/yr)

R-134a mole number



### • T=50°C

0 200 400 600 800 1000 1200

0 10 20 30 40 50 60

0 2 4 6 8 10 12 14 16 18 20 22 24Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

02/05/08 - MAC system C LFR@50°C : 35.4 g/yr LFR(g/yr)

R-134a mole numberEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 23 - 

### Appendix 4: Leak flow rate and mole number graph MA C system D

• T=30°C

0 200 400 600 800 1000 1200 1400 1600

0 10 20 30 40 50 60 70 80 90 100

0 5 10 15 20 25 30 35Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

23/01/08 - MAC system D LFR@40°C : 28.4 g/yr LFR(g/yr)

R-134a mole number



### • T=40°C

0 200 400 600 800 1000 1200 1400 1600

0 10 20 30 40 50 60 70 80 90 100

0 2 4 6 8 10 12 14 16 18 20 22 24 26Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

25/01/08 - MAC system D LFR@40°C : 49,1 g/yr LFR(g/yr)

R-134a mole number



### • T=50°C

0 500 1000 1500 2000 2500 3000

0 10 20 30 40 50 60 70 80 90 100

0 2 4 6 8 10 12 14 16 18 20 22 24Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

28/01/08 - MAC system D LFR@50°C : 95.3 g/yr LFR(g/yr)

R-134a mole numberEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 - 24 - 

### Appendix 5: Leak flow rate and mole number graph MA C system E

• T=30°C

0 200 400 600 800 1000

0 10 20 30 40 50 60 70 80 90

0 2 4 6 8 10 12 14 16 18 20Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

14/02/08 - MAC system E LFR@30°C : 24.2 g/yr LFR(g/yr)

R-134a mole number



### • T=40°C

0 200 400 600 800 1000 1200 1400 1600 1800

0 10 20 30 40 50 60 70 80 90

0 2 4 6 8 10 12 14 16 18 20 22 24 26Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

15/02/08 - MAC system E LFR@40°C: 45.3 g/yr LFR(g/yr)

R-134a mole number



### • T=50°C

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

0 10 20 30 40 50 60 70 80 90

0 2 4 6 8 10 12 14 16 18 20 22 24Q(mole E-6)LFR(g/yr)

Time (hr)

Leak flow rate LFR (g/yr) & mole number Q(mole)

16/02/08 - MAC system E LFR@50°C: 82.3 g/yr LFR(g/yr)

R-134a mole numberEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -25 - 

### 2. Analysis of current recharge by non professional s in California

2.1 Introduction

In order to evaluate the potential impact of HFC-13 4a emissions from non-professional servicing of MVAC systems, the ARB commissioned the CEP for a study including field tests in order to measure refrigerant emissions during 50 real refill ing operations of MVAC systems.

The research project aims to identify emission rate s due to non-professional servicing as compared to professional servicing based on servici ng operating modes observed in the State of
California.

Given enough time, a leaky MVAC system will release its entire refrigerant content to the atmosphere if the refrigerant leak is significant. The MVAC system leak flow rates imply one or more recharge(s) of the MVAC system during the vehi cle’s lifetime. During a charging process, refrigerant emissions could be classified into two categories:

 

### Direct emissions due to leaks from 

### disposable containers (cans or cylinders), hoses, and fittings; or

 

### Heel emissions due to the refrigerant remaining in the disposable containers after charging.

Section 2.2 describes the disposable small cans ava ilable on the Californian market, including contents, prices, and types. Leaks before and afte r use of some can samples have been measured in the laboratory and are presented in Sec tion 4.2.

Analysis of current recharge by non-professionals, Do-It-Yourselfers (DIYers), in California is presented in Section 2.3. The know-how and the exp ert skills have to be taken into account when drawing conclusions. Two sampling groups of n on-professionals are considered and classified based on their qualifications. Analyses will be made for each sampling group as well as for the non-professional DIYers who have recharg ed different MVAC systems.



### 2.2 Small cans: description and leak test results

2.2.1 Small can description

Two categories of small cans (SC) are available on the Californian market:

 Screwed and Perforated Cans (S&P) (Photo 2.1)

 Cans equipped with a valve and an optional pressur e gauge (V-type) (Photo 2.2)

S&P cans are available in different capacities: 12, 13, 14, 18, and 19 oz. V-type cans are available in 14 oz and 19 oz capacities.

Photo 2.1 S&P Can Photo 2.2 Can equipped with a va lve and pressure gauge. Photo 2.3 Re-usable charging kit for
S&P small cans.



### S&P cans are connected to a charging kit. Photo 2. 3 presents an example of a charging kit. This charging kit is usually composed of:Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -26 - 

###  Can tap: perforating valve, with a screw fitting

 Flexible hose

 Service valve adaptor: low-pressure fitting

 Pressure gauge (optional)

Table 2.1 lists a large variety of small cans avail able on the Californian market, their type, content, market price, and online price. A list of small cans and their characteristics is presented
in Annex A.

Table 2.1 Small cans details.

SC brand name Model Type Content Price Kragen Price Kragen 2 Price Net

www.partsamerica.com/

Quest Normal S&P 12 oz 7.99 $

Quest UV S&P 12 oz 11.99 $

Quest Stop Leak S&P 12 oz 11.99 $

Quest Sub Zero Polar

Bear S&P + reusable

kit 19 oz 28,99 $ 25.99 $ $24.99

Johnsen S&P 12 oz 7,99 $ 8.99 $ $8.99

Johnsen UV Dye S&P 12 oz 14.99 $
Interdynamics EZ Chill Valve equipped 14 oz 21,99 $ 17.99 $

Interdynamics Arctic Freeze S&P 13 oz 13.99 $ $12.99

Interdynamics Arctic Freeze Valve equipped

+ gauge 12 oz 39.99 $

Interdynamics Arctic Freeze Valve equipped 19 oz $32.99

Interdynamics Arctic Freeze with

Reusable Trigger Valve equipped 14 oz $26.99

Interdynamics EZ Chill+hose Valve equipped 28.99 $

Interdynamics EZ Chill

Measure/Recharge
Kit Valve equipped

+ gauge 19 oz $24.99

Interdynamics Arctic Freeze S&P 18 oz $27.99



### To conclude, the S&P cans are cheaper than the V-ty pe cans The S&P price varies according to the refrigerant content and the brand name. In order to save money people prefer to buy the charging kit once and then reuse it with S&P cans. It should be noted that the S&Ps are dominant (nearly 90% of the market, as assessed by several dealers) for two reasons: the more knowledgeable DIYers buy S&Ps due to the ease of us e; less knowledgeable, but price-oriented
DIYers also choose S&Ps.



### 2.3 Analysis of recharge by do-it-yourselfers (DIYe rs)

The aim of this section is to determine refrigerant emissions when a MVAC is charged by a DIYer. When charging their own car, a DIYer releas es direct and indirect refrigerant emissions into the atmosphere. Direct emissions are those em itted during the charging process (leaks from the hose, can tap, and service valve adaptor). Indirect emissions, known as “heel emissions”, are refrigerant remaining in the can af ter the DIYer has disconnected the service valve adaptor. If the kit is leaking, sooner or la ter the refrigerant remaining in the can will be released. An operating procedure needs to be devel oped in order to assess the different refrigerant emissions and the effective refrigerant mass charged in the MVAC.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -27 - 

### 2.3.1 Operating procedure for emission assessment

The operating procedure used to evaluate refrigeran t emissions was carried out according to the following method described below:

 The CEP team performs an initial refrigerant recov ery. The refrigerant charge of the MAC system is recovered (and weighed) in order to evalu ate the efficiency of the charge operation made by the SCU (small can user).

 The CEP team partially charges the AC loop (typica lly 1/3 of the original charge), in order to perform the charging process under realistic condit ions: the pressure is the R-134a saturating pressure.
Note: If the system is evacuated and maintained under a r elative vacuum, the charge with small cans is not representative of the usual use.



###  Before the beginning of the SCU operation, differe nt types of small cans are displayed to the individual. The SCU is free to choose one, or sele ct the type that he usually uses for charging the AC system.

 The SCU proceeds in charging his AC system. He is free to use the number of small cans he wants. The CEP personnel take mental notes of t he operation steps. After the operation is complete, the description is written on a dedica ted field report.

 The CEP evaluates the refrigerant emissions during the charging process as well as the can heels. Can heels are measured by weighing the can before charging and after charging, and
before the de-connection from the service valve. W hen the can cannot be weighed because the SCU dismounts it right away, emissions are incl uded in the operation.

 The SCU is interviewed on his usual practice with small cans (periodicity of use, etc.) and some advice is given.

 The CEP team recovers the refrigerant from the MAC system after the charging process and the effective refrigerant mass charged into the sys tem is known by the difference.



### 2.3.2 Descriptions of the small can user sample

The number of DIYers participating in this study is 50. This includes 5 persons who have been interviewed, but who have not performed the charge. They have answered the questions describing what they usually do for charging. The other 45 persons performed the charging procedure, either on their own vehicles or on the C EP cars. The 50-person sample is divided into two sampling groups. The first one takes into account the 30 cases presented in the first intermediate report (October 2007). The second sam pling group gathers the remaining 20 cases done after the first report was presented. T he second sampling group is comprised of persons who are relatively familiar with small cans

.

Conclusions are consequently drawn for the two samp ling groups as well as for the overall sample. Conclusions are intentionally divided into three groups in order to take into account the effect that experience and knowledge has on the ref rigerant release.

Sample 1 This sample includes 30 persons who have been inte rviewed, observed doing the charging process (5 persons), and those who perform ed the charging procedure, either on their own vehicles or on the CEP cars (25 persons). The 25 cases include:

 

### 16 persons (all not SC experts), who have charged t he MAC system on their own vehicles,

 

### 6 others persons, who have made the refrigerant cha rge of the CEP rental car (Chevrolet), and,

 

### 3 others who have made the refrigerant charge on a 1990 Cadillac Deville purchased by
CEP.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -28 - 

### Sample 2 This sample includes 20 cases where the charging p rocess was made on a 1999 Mitsubishi Montero owned by CEP. The CEP team aske d for help from persons near auto-parts stores due to the malfunctioning of the Mitsubishi MVAC system. 17 persons performed the operation, while 3 people told the CEP staff how to re-charge the air conditioner. The CEP team performs exactly what the person asks him to do.

Small can user sample (30 cases)

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Male Female <30 yr old >30 yr old User of SCNon user o f

SCNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Smaple percentage Small can user sample (20 cases)

0 2 4 6 8 10 12 14 16 18 20 22

Male Female <30 yr old>30 yr old Expert User of

SC Non user

of SCNumber of vehicles

0% 20% 40% 60% 80% 100%Sample percentage

Figure 2.1 Small can users - Sample 1. Figure 2.2 S mall can users - Sample 2



### The first sample of small can users are mainly comp osed of males. Two saleswomen working at the Kragen auto-parts store helped the CEP team to fill their car while simulating a defective AC. 23 persons are older than 30, and 5 are familiar wi th car self-servicing, but they are not experts in air conditioning (see Figure 2.1). 67% of the 3 0 persons declared that they had already used
small cans on their car air conditioner. The other s have never used small cans before, but they were interested either for curiosity or for saving money by avoiding professional service.

For the second sample, all persons are men, among w hom 12 are older than 30. 80% of the 20 persons acknowledged the use of SC. They had made the charging procedure on their own car or on a family member car before or, at least, they watched someone doing it before. The second sample comprises a large proportion of users familiar with SCs compared to the first sample (see Figure 2.2).

Small can user sample (50 cases)

0 5 10 15 20 25 30 35 40 45 50

Male Female <30 yr old >30 yr old User of SCNon user o f

SCNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Sample percentage

Figure 2.3 Small can users – All 50 cases SC: Small Cans
SCU: Small Can Users



### Now, considering the whole sample of 50 persons, mo re than 72% of the sample has used a small can before (see Figure 2.3). 40% are familia r with car self-servicing, meaning that theyEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -29 - 

### know how to proceed in recharging the MVAC (neverth eless they can sometimes make wrong operations). 

### 2.3.3 Vehicle analysis

Figure 2.4 illustrates the car vintage of the 30 ca ses studied in the first sample. Five vehicles were originally filled with R-12 (vintage 1990 and 1991), but the retrofit to R-134a had been done previously, and the AC loop was equipped with an R- 134a fitting when the charge with the small
can had been done. The 5 cases on retrofitted R-12 vehicles included the three refrigerant chargings of the CEP Cadillac. The CEP rental car (Chevrolet) has been used 8 times (2 times for interviews and observing people helping the CEP team, and 6 times for a charging procedure). The Cadillac is used three times for t he charging process.

The 20 cases in Sample 2 were performed on the 1999 Mitsubishi Montero.

The overall number of recharging procedures made is 45, distributed as follows:

 16 times on different vehicles owned by the DIYers

,

 6 times on the CEP rental car (Chevrolet),

 3 times on the CEP Cadillac Deville and

 20 times on the CEP Mitsubishi Montero.

Car vintage of the 16 vehicles owned by the DIYers

As shown on Figure 2.4, most cars were less than 10-years old. When looking at Figures 2.4 and 2.5, one may wonder
if the older car had the lower refrigerant charge. In fact,
the distribution of low refrigerant charges remaining in the MAC system is not related to the car vintage.

0 1 2 3

1991

1 99 2 1993 1994

1

9 9 5 1996 19

9 7 1998

1

9 99 200 0 2001 20

0 2 2 0 03 2004 2

0 0 5 2 0 06Number of Vehicles

Figure 2.4 Car vintage for the 16 vehicles owned by the DIYers.

Initial charge/nominal charge (16 cases)

0 1 2 3 4 5 6

0 % t o 1 0 %

1 0 % t o 2 5 %
2 5 % t o 5 0 %
5 0 % t o 7 5 %

7 5 % t o 1 0 0 %Number of vehicles .

0%

5% 10% 15% 20% 25% 30% 35%Sample percentage . Period before last refrigerant refill (16 Cases)

0 1 2 3 4 5 6 7

1/2 year 1 year 2 years 3 years 4 years 10 years NDNumber of vehicles .

0% 5% 10% 15% 20% 25% 30% 35% 40%Sample percentage .

Figure 2.5 Initial charge / nominal charge before the SC charging. Figure 2.6 Periodicity of small can use.



### ND: Not DefinedEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -30 - 

### Figure 2.5 shows the initial charge of each vehicle , measured before the charging process with a small can. It indicates the number of vehicles (le ft scale) and the percentage on the sample (right scale). They are classified in categories d epending on their initial refrigerant content (x axis).

Two vehicles were nearly empty of refrigerant befor e the operation. One third of the sample had an initial refrigerant charge between 75% and 100% of the nominal charge. One quarter of the sample had their AC working with a charge between 5 0% to 75%. 45 % have their system either working very badly (25%) or not working at all (20% ). Nearly 45% of the sample check their AC annually (see Figure 2.6). After the recovery, all AC systems have been evacuated and recharged with a partial charge (1/3 of the corresp onding nominal charge).



### 2.3.4 Charging procedure evaluation

Choice of small can

DIYers have to choose the small can type they want. Most of them chose the “screwed and perforated” type. 77% and 80% chose the S&P type r espectively for Samples 1 and 2 (see Figures 2.7 and 2.8). The 12-oz capacity can, the smallest available, is preferred to the others, representing nearly 64% of the overall sample (see Figure 2.9).

Type of small can used (30 cases)

0 2 4 6 8 10 12 14 16 18 20 22 24 26

perforated &

screw ed valve

equipped 12oz 14 oz 18 oz 19 ozNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80%Sample percentage Type of small can used (20 cases)

0 2 4 6 8 10 12 14 16 18

perforated &

screw ed valve

equipped 12oz 13 oz 14 oz 19 ozNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%Sample percentage

Figure 2.7 Type and capacity of small can chosen by

the users (Sample 1). Figure 2.8 Type and capacity of small can chosen by the users (Sample 2).

Type of small can used (50 cases)

0 5 10 15 20 25 30 35 40 45

perforated

& screw ed valve

equipped 12oz 13 oz 14 oz 18 oz 19 ozNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%Sample percentage SC selection criteria

0 2 4 6 8 10 12 14

simpler to

use Have

used the

same can type

before have

already

the charge kit cheaper bigger

capacity pressure

gauge equipped no

responseNumber of Vehicles

0%

5% 10% 15% 20% 25% 30% 35% 40% 45%Sample percentage

Figure 2.9 Type and capacity of small can chosen by the users (overall sample). Figure 2.10 Criteria for small can type choice.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -31 - 

### Figure 2.10 indicates criteria used by DIY individu als in selecting the type of container. The most frequent one is that the individual already possess es an S&P charging assembly and naturally selects an S&P-type container. Referred to in Tabl e 1.1, the price of the valve-equipped can is two to three times higher than that of the S&P can. In addition if the SCU wants to use more than one can, he would prefer to buy the S&P with t he reusable charging kit.

Based on the number of persons who had already perf ormed the procedure on their own vehicles, 63% of small can users decided to recharg e their AC because of lack of cooling performance (see Figure 2.11). This fact is consis tent with the analysis of the refrigerant content (see Figure 2.5) before servicing: two third of the sample have an initial refrigerant content lower than 75% of the nominal charge. Nearly half of the fleet was below a 50% refrigerant nominal charge.

Refrigerant nominal charge knowledge yes 26%

no 74%

Figure 2.11 The reasons to use a small can. Figure 2.12 Knowledge of the AC nominal charge.



### Only 26% of the small can users know the mass of re frigerant to be filled in their system (see Figure 2.12). Among the selection criteria announc ed by the DIYers, it is amazing that none of them relates the can capacity to the vehicle’s orig inal charge. All criteria that DIYers take into account are mentioned in Figure 2.10.

In fact, the can capacity should be an important cr iterion for the DIYer when choosing a SC because the can capacity is directly linked to the system nominal charge (announced by the manufacturer) and to the remaining AC system charge . A system whose nominal charge is 900 grams needs two or more 12-oz cans.

Indeed, the information and equipment available to DIYers are usually too limited to allow them to know how much refrigerant to add or when the sys tem is fully charged. This lack of
information can lead to the ineffective use of smal l cans as well as the inappropriate charging of the MVAC system.

Charging procedure

No instructions were given to small can users durin g their operation. They were observed and the facts and actions are reported on in Figures 2. 13 to 2.15 respectively for the first, second, and overall samples.

Sample 1 people seem to be less familiar with SCs a s compared to those of Sample 2. The following criteria verify this observation.

Reading instructions chart : Nearly 67% of people read the instructions in Sam ple 1 compared to 35% in Sample 2. Usually they think they already k now what to do and many times do not read the instructions any more.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -32 - Sample 1

Figure 2.13 Report of facts and actions during the charging process of small can users (sample 1).



### Engine on or off

: several persons in Sample 1 did not turn on the e ngine (18%) or the AC system (20%) as shown in Figure 2.13. In contrast, all pe rsons of Sample 2 did turn on the engine and the AC system (see Figure 2.14).

Shaking the can : 75% of Sample 2 shook the can during charging, wh ile only 50% did in Sample1. Sample 2

Figure 2.14 Report of facts and actions during the charging process of small can users (Sample 2).
Note : Nearly all SCUs when shaking the can were shaking it strongly. Some were shaking the can from the vertical to the horizontal position, and others were only shaking it with small amplitude (not mov ing it up to the horizontal position). In any case, the r efrigerant charge is a two-phase flow.



### Nevertheless, only 75% of Sample 2 correctly perfor med the procedure compared to 48% for Sample 1. These values reflect that the familiarit y with SCs is not a sufficient condition to charge correctly.

Now, considering the overall sample, more than 58% proceeded correctly by turning on the engine and the AC, and shaking the can from horizon tal to vertical positions in order to charge in both the liquid and vapor phases.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -33 - 

### Note : When the loop is equipped with a suction line acc umulator, charging in liquid phase is not dangerous for the compressor. But if there is a HP receiver associated with a thermal expansion valve (TxV), it could damage the compressor (liquid slugging).

Figure 2.15 Report of facts and actions during the charging process of small can users (overall sample).



### Criteria to stop charging the AC

Criteria to stop charging with small can (50 cases)

0 5 10 15 20 25 30PressuregaugeAirtemperatureChargingtimeThe can isemptyBubbles onthe HPreceiverNumber of vehicles

0% 10% 20% 30% 40% 50% 60%Sample percentage

Figure 2.16 Diagnostic to stop charging.



### Small can users were asked why they decided to stop charging the AC system. They could have answered one or two reasons (the number of ans wers is higher than the number of users). The air temperature at the AC outlet and verificati on by shaking the can to determine if liquid remained in the can were the most frequent reasons for stopping the recharge. Fifty percent measured the blown air temperature in the car to ma ke sure the cooling was effective. The measure is subjective as they did not use any tempe rature sensor. Fifty percent stopped the charge when the can was empty. They would shake th e can to see if it was empty; while others felt the can temperature: when the can was still co ld, some refrigerant remained.

Note : Fifty percent answered that they stopped charging when the can was empty, but this fact does not mean that the cans were empty at the end o f the different operations.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -34 - 

### For cans equipped with a pressure gauge indicator, some of the people who read the
instructions written on the cans followed the instr uction that the charge is complete when the “Pressure ranges between 25 psi and 40 psi”. More than 35% of the answers are based on this criterion (see Figure 2.16). The pressure gauge in dicates only the low-side system pressure showing different values and colors to indicate whe n the system is “undercharged”, “full”, or “overcharged” with refrigerant. But the system con dition is dependent on more than just the amount of refrigerant in the MVAC system. The low- side pressure gauge indicates that refrigerant is circulating in the MVAC system and n ot the amount. A low-side gauge pressure of zero would indicate an empty system. Therefore, th e kit gauge reading does not provide the
information needed to determine the amount of refri gerant needed or the criteria to stop charging. On the contrary, wrong readings are deli vered through the tag and the gauge.

Number of cans used to complete the refrigerant cha rge

Number of cans used during the filling process (30 cases)

0 2 4 6 8 10 12 14 16 18 20

1 can 2 cans 3 cansNumber of vehicles

0% 10% 20% 30% 40% 50% 60%Sample percentage Number of cans used during the filling process (20 cases)

0 2 4 6 8 10 12 14 16 18 20

1 can 2 cans 3 cansNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Sample percentage

Figure 2.17 Cans used during charging (Sample 1). F igure 2.18 Cans used during charging (Sample 2).



### The number of cans used during the charging process is directly related to the knowledge and the qualification of the user. In fact, without ma king a complete recovery, nobody can evaluate or estimate the quantity of refrigerant to be charg ed. Moreover, because the exact refrigerant mass that has been charged is also unknown, the num ber of cans is based on random issues. It may be that certain small can users are very cautio us and use only a single can in order to avoid a major loss of refrigerant due to a significant le ak or leaks. Another consideration would be over-charging which may damage the system. Obviously, in Sample 1 more
SCUs have used more cans than in Sample 2. 63% have used 1 can compared to 95% in Sample 2. Two of the three
SCUs who used three cans did not proceed correctly.
Most of small can users choose the smaller capacity cans (12 oz) (see Figure 2.9).

As shown in Figure 2.19, nearly 76% of operations were
done with 1 can. 18% of operations were done with 2 cans and only 6% with 3 cans. Number of cans used during the filling process (50 cases)

0 5 10 15 20 25 30 35 40

1 can 2 cans 3 cansNumber of vehicles

0% 10% 20% 30% 40% 50% 60% 70% 80%Sample percentage

Figure 2.19 Cans used during charging (overall samp le).Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -35 - 

### Refrigerant charging time

Here again, a DIYer familiar with SCs will recharge the system in 5 to 10 minutes. In fact, the charging time depends on both the filling mode (liq uid or vapor) and on the can size. The regular time for charging a 12-oz small can, applyi ng the correct procedure (continuous shaking), is 5 minutes. The time is longer when th e can is not shaken and 15 minutes is insufficient to evaporate the complete content of t he can in the upright position. Most cases that take longer than 20 minutes are done with more than 1 can.

Charge operation duration

0 2 4 6 8 10 12

1 5 10 15 25 40

MinutesNumber of operations .

0% 5% 10% 15% 20% 25% 30% 35% 40%Sample percentage . Charge operation duration (20 cases)

0 1 2 3 4 5 6 7 8 9 10

1 5 10 15 25 40

MinutesNumber of vehicles

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%Sample percentage

Figure 2.20 Refrigerant charging time (sample 1). F igure 2.21 Refrigerant charging time (sample 2).



### 50% of Sample 1 SCUs charged the MVAC in the uprigh t position (vapor phase only). This explains why the most frequent charging time is 15 minutes (see Figure 2.20). Only 30% of the operations took between 5 and 10 minutes.

In contrast, 75% of Sample 2 SCUs charged while sha king the can from vertical to horizontal positions. The most frequent charging times are 5 and 10 minutes, which is consistent (see Figure 2.21). 40% of operations took 10 minutes an d 35% took 5 minutes.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -36 - 

### Figures 2.20 and 2.21 indicate that two cases in Sa mple 1 and one case in Sample 2 completed, charging operations in only 1 minute. There are tw o reasons for the shortness of these operations:

 The SCU reads the pressure gauge indicator and sto ps charging because the pressure seems to be correct. The charge with a small can i s limited to the pressure equilibrium. In this case most of the refrigerant remains in the can.

 The operator does not recognize how to proceed, so he stops the operation shortly after the beginning.

Charge operation duration (50 cases)

0 2 4 6 8 10 12 14

1 5 10 15 25 40

MinutesNumber of operations

0% 5% 10% 15% 20% 25%Sample percentage The can is kept for a later use

yes
35%

no
65%

Figure 2.23 Part of people who keep the

can after use.
Figure 2.22 Refrigerant charging time (overall samp le).



### Considering the charging time for the overall sampl e, nearly 50% took from 5 to 10 minutes. 5%
took less than 1 minute and 5 % took more than 40 m inutes. Cases where the charging process took 25 minutes are due to two reasons: vapor charg ing or more than one can has been charged.

After the charging operation, some refrigerant may remain in the can, and especially when the can capacity is large, or when the charging operati on is performed in vapor phase. When the SCU is using a small can equipped with a valve, the can is reusable. But in the case of perforated cans, refrigerant is completely released when disconnecting the can. According to the field survey, two thirds of SCUs declare they w ill not keep the can after use (see Figure 2.23).



### 2.3.5 Refrigerant emissions associated with the use of small cans

Refrigerant emissions during the charging process

As presented in Section 2.3, the total number of ve hicles tested was 45 including the 16 vehicles owned by the SCUs and 29 operations being done on t he CEP cars.

The initial refrigerant content of the MAC system i s known. The small can has been weighed before and after the charging process. The differe nce corresponds to the refrigerant mass released from the can: the first part is filled in the AC circuit; the second part is released during the charging process.

Once the refrigerant recovery is performed, the pre cise system charge using the small can is measured by difference with the known initial charg e (1/3 of the original charge). The difference between the refrigerant contained in the can (initi al weighing), and the refrigerant mass reallyEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -37 - 

### filled in the MAC circuit is the refrigerant emissi on during the charging process, plus the refrigerant heel remaining in the can.

Figures 2.24 to 2.29 illustrate emissions in grams (g) due to servicing the can heel as well as the overall emissions for the overall sample (45 cases) . Results corresponding to Samples 1 and 2 alone are presented separately in Annex B.

Emissions due to servicing

0 2 4 6 8 10 12 14 16 180g to 5g5g to 10g10g to 50g50g to 100g100g to250g250g to500gmore than500gNumber of vehicles

0% 5% 10% 15% 20% 25% 30% 35% 40%Sample percentage Emissions due to servicing

0 100 200 300 400 500 600 7000g to 5g5g to 10g10g to 50g50g to 100g100g to250g250g to500gmore than500gg

0% 5% 10% 15% 20% 25%Mass percentage

Figure 2.24 Number of vehicles as a function of emission range due to servicing (overall sample). Figure 2.25 mass emission as a function of emission range due to servicing (overall sample).



### Figure 2.24 presents the classification of operatio ns as a function of emission range due to servicing for the overall sample composed of 45 ope rations. For 16 cases, representing 36% of the sample, small emissions have been observed: bet ween 0 and 5 grams.

A few charging operations (five cases, or 10%) were very leaky and lead to massive releases of refrigerant (over 100 g):

 A great number of cans equipped with valves as wel l as some charging guns for S&P type (F1-13 illustrated in Section 1) are very leak y and are not very convenient to use. The valve is very leaky and frequently liquid refri gerant was released at the connection when the can is put upside down.

 When the operator is using 2 or more “screwed type ” small cans, the release of refrigerant remaining in the first can be significa nt, if the can is not empty (filling in vapor phase, without shaking).

Figure 2.25 illustrates the emissions during servic ing classified by emission ranges. Emissions from 0 to 10 g represent 54% of the sample. In con trast, these emissions represent only 4% of the total mass emitted during the charging process on a mass basis.

The major part of emissions (64%) is due to high re leases, over 100 g, which represents only five of the sample cases. One non-correct operatio n done without care could release as much as 20 correct operations. 33% of the overall mass emissions range between 10 and 100 grams. Refrigerant emissions the during charging process, which lead to a mass loss higher than 50 g, represent nearly 86% in mass of the total refrigera nt emissions, but only 26% of the sample. The total mass emitted due to servicing represents nearly 16% of the sum of the refrigerants charged inside AC systems.

Can heels

At the end of the charging process, the refrigerant remains inside the can (valve equipped) or is released to the atmosphere if the charging kit is u nscrewed (in case of S&P cans). DependingEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -38 - 

### on the charging process (shaking or not shaking the can, filling the AC system in the liquid or vapor phase) the refrigerant in the can heel is sig nificant or not.

Can heel

0 2 4 6 8 10 12 14 160g to 5g5g to 10g10g to 50g50g to 100g100g to250g250g to500gmore than500gNumber of vehicles

0% 5% 10% 15% 20% 25% 30% 35%Sample percentage Can heel

0 500 1000 1500 2000 2500 30000g to 5g5g to 10g10g to 50g50g to 100g100g to250g250g to500gmore than500gg

0% 10% 20% 30% 40% 50% 60%Mass percentage

Figure 2.26 Number of vehicles as a function of can

heel range (overall sample). Figure 2.27 Mass emission as a function of can heel range (overall sample).



### When the charging process is done correctly, the ca n is more likely empty at the end and the heel is low (between 0 to 10 g). This represents 3 1% of the operations that sensibly meet in the number of persons who did the operation correctly ( 32%).

62% of operations are done with the can heel lower than 50 g, which represent only 7% of the total heel (see Figure 2.27). 38% of operations ar e not properly done (can heel is larger than 50 g) but represent more than 90% of the overall ca n heel. The total heel resulting represents nearly 33% of the sum of the refrigerants filled in side AC systems.

Overall refrigerant emissions

Figures 2.28 and 2.29 illustrate the total refriger ant emissions coming from emissions due to servicing as well as from the can heels after charg e, measured during the 45 operations performed by small can users.

Total refrigerant losses

0 2 4 6 8 10 12 14 160g to 5g5g to 10g10g to 50g50g to 100g100g to250g250g to500gmore than500gNumber of vehicles

0% 5% 10% 15% 20% 25% 30% 35%Sample percentage Total refrigerant losses

0 500 1000 1500 2000 2500 30000g to 5g5g to 10g10g to 50g50g to 100g100g to250g250g to500gmore than500gg

0% 5% 10% 15% 20% 25% 30% 35% 40%Mass percentage

Figure 2.28 number of vehicles as a function of tot al refrigerant emissions (overall sample). Figure 2.29 mass emission as a function of total refrigerant emissions (overall sample).



### Refrigerant emissions that are less than 10 g (13% of cases) represent a total refrigerant release of less than 1% on a mass basis (see Figure 2.29). Large releases of refrigerant (more than 250Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -39 - 

### g per operation) represent 43% of the sample observ ed (45 vehicles and small can users), but it represents 78% on a mass basis.

Refrigerant mass repartition and ratios

Sample 1 (25 cases) In Sample 1, the total mass of refrigerant containe d in small cans before the charging operation is 14,395 g, corresponding to an average value of 5 75 grams per vehicle. The effective refrigerant mass charged in the vehicle is 8,557 g (342 g/vehicle) and represents 59% of the total initial mass. In contrast, the total refrige rant emissions due to servicing are 1,830 g (73 g/vehicle) representing 13% of the total initia l mass. Moreover, the total can heel is 4,009 g (160 g/vehicle), which represents 28% of the total initial mass (see Figures 2.30 and 2.31).

Refrigerant mass

0 2000 4000 6000 8000 10000 12000 14000 16000

Effective mass charged Leaks due to

servicing Can heel SUMMass (g)

0 100 200 300 400 500 600Mean values per vehicle (g) Refrigerant ratio

59%

28%

13% Effective mass charged
Leaks due to servicing

Can heel

Figure 2.30 Refrigerant mass repartition (sample 1) . Figure 2.31 Refrigerant ratio (sample 1).



### From the first sample, it could be concluded that D IYers who are not-familiar with small cans,
lead to overall emissions of about 68% of what has been charged inside the MVACS.

Sample 2 (20 cases) In contrast, when the DIYers are familiar with smal l cans, the overall emissions are about 21% of the effective mass charged.

Refrigerant mass

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Effective mass charged Leaks due to

servicing Can heel SUMMass (g)

0 50 100 150 200 250 300 350 400 450Mean values per vehicle (g) Refrigerant ratio

82% 11%

7% Effective mass charged
Leaks due to servicing

Can heel

Figure 2.32 Refrigerant mass repartition (sample 2) . Figure 2.33 Refrigerant ratio (sample 2).



### For sample 2, the total mass of refrigerant contain ed in small cans before the charging operation is 7,626 g, corresponding to an average value of 38 1 g/vehicle. The effective refrigerant massEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -40 - 

### charged in vehicles is 6,280 g (314 g/vehicle) and represent 82% of the total initial mass. In contrast, the total refrigerant emissions due to se rvicing are 512 g (25 g/vehicle) representing 7% of the total initial mass. Moreover, the total can heel is 834 g (41 g/vehicle), which represents 11% of the total initial mass (see Figur es 2.32 and 2.33).

Overall sample (45 cases)

Considering the overall sample, that covers a wide range of randomly chosen people, the values
obtained are in the middle between those obtained f or Samples 1 and 2. Overall emissions are about 48% of the effective mass charged.

Refrigerant mass

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000

Effective mass charged Leaks due to

servicing Can heel SUMMass (g)

0 50 100 150 200 250 300 350 400 450 500Mean values per vehicle (g) Refrigerant ratio

67%

22%

11% Effective mass charged
Leaks due to servicing

Can heel

Figure 2.34 Refrigerant mass repartition (overall

sample). Figure 2.35 Refrigerant ratio (overall sample).



### The total mass of refrigerant contained in small ca ns before the charging operation is 22,021 g, corresponding to an average value of 490 g/vehicle. The effective refrigerant mass charged in vehicles is 14,837 g (330 g/vehicle) and represents 67% of the total initial mass. In contrast, the total refrigerant emissions due to servicing are 2, 341 g (52 g/vehicle) representing 11% of the total initial mass. Moreover, the total can heel i s 4,842 g (108 g/vehicle), which represents 22% of the total initial mass (see Figures 2.34 and 2.3 5).

Values to remember

 

### 67% of initial mass contained in the cans are effec tively charged into the system,

 

### 11% are directly emitted during the charging proced ure,

 

### 22% remain in the can as heel. Sooner or later, th ey will be released to the atmosphere.



### 3. Analysis of current leak search and recharge by professional servicing in
California

3.1 Introduction

The aim of this section is to analyze the refrigera nt leak search as well as the recharging procedure done by professional servicing in Califor nia. In fact, a consumer unfamiliar with auto servicing, whose MAC system presents a partial or f ull failure, will mandate a professional in order to repair it.

A MAC failure on a CEP car has been simulated by ha ving an empty or partially empty system. The overall professional procedure is described ste p by step from the preliminary AC check until the charge of the system. The operating mode of th e service technician will be carefullyEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -41 - 

### described. After the charge, the CEP team recovers carefully the refrigerant in order to evaluate the accuracy of the recharge compared to the origin al system charge.

50 garages or AC repair centers have been considere d in different areas in California in order to cover a wide range of cases. Garage visits and ope rations are detailed in Annex C.



### 3.2 Operating procedure to perform professional ser vicing analysis

3.2.1 Simulation of AC failure

A first proposal was to use rental cars to proceed and analyze the current professional servicing. Due to regulations, the CEP team was not allowed to use such vehicles nor operate on the AC system.

The first two operations were done using the CEP Ca dillac Deville. The CEP team was obliged to use a different vehicle for the following reason s:

 as mentioned previously, the Cadillac AC system ra n originally with R-12 refrigerant and
had been retrofitted to R-134a

 two leaks were detected, the first one on the HP s ervice valve, the other one on the compressor suction port

 after visiting two garages, the compressor clutch stopped operating.

Note: one professional declined to make any repair on this system (because of the retrofit from R-12 to R-134a); thus, when a professional declines , the only way for charging such a system is
to use small cans.

For this reason, the CEP team had to buy a vehicle running on R-134a. All other visits (48 visits) at professional garages have been made using the CE P Mitsubishi Montero.

Two criteria motivated the choice of the Mitsubishi . The first and main criterion is the accessibility of the high and low-pressure servicin g valves. The second one is the large cargo space available in the Mitsubishi Montero, which ha s been very useful to carry the CEP equipment.

In order to ask mechanics to repair the system, fai lure had to be simulated. The failure organized by the CEP team simulated real operating defaults of the MAC system. Two failures
have been considered and are described below.

 The CEP team partially charged the MAC system with refrigerant. The mean refrigerant mass charged is around 100 grams. The MAC system d id not present any leakage, rupture or malfunctioning. 43 cases were considered partia lly empty.

 The other 7 cases were similar to the first ones, but the system was emptied down to residual pressure equal to atmospheric pressure.



### 3.2.2 Description of the MACS used

The Mitsubishi Montero AC is a single-evaporator sy stem using a thermal expansion valve with a parallel flow condenser and a fixed displacement compressor. The HP and LP service valves are easily reachable as shown in Photo 3.1.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -42 - 

### The arrangement of AC components is also indicated on Photo 3.1. A scheme of the Montero AC system is shown in Figure 3.1.

Photo 3.1 Under hood view showing the arrangement o f the AC system components.

Figure 3.1 Schematic view of the Mitsubishi Montero AC system.



### The potential leak sources on the Montero AC system are circled in red on Figure 3.1 and are as
follows:

 The compressor rotating lip seal

 The compressor suction and discharge ports

 The inlet and outlet of the condenser, evaporator, and TxV

 The liquid receiver inlet and outlet

 The HP and LP service valvesEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -43 - 

###  Fittings on the suction line and on the liquid lin e

 The high-pressure sensor

 The relief valve

Using an electronic detector, the CEP team performe d a leak search on the MACS in order to check the system leak tightness. All parts and con nections are verified. The whole system is tight except at the TxV where a very small leak is detected.



### 3.2.3 Selection of professional garages and sample description

50 garages have been visited in California. Garage s are located in different areas in order to collect a wide sample, especially in Los Angeles an d San Diego (see Figure 3.2).

Figure 3.2 Location of garages visited in Californi a.

Garage size (50 cases)

0 2 4 6 8 10 12 14 16 18 20 22 24 26

N <= 2 2 < N < 5 N >= 5Number of cases

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%Sample percentage 

### Figure 3.3 shows the repartition of garages by size (technician number). 38 % of garages
consist of 2 or 1 techn icians.
46 % have 3 or 4 technicians. The remaining 16% have 5
technicians or more.

N: Number of technicians Figure 3.3 Garage sizes based on the number of tech nicians.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -44 - 

### 3.3 Analysis of current leak search and recharge by professional servicing

3.3.1 Preliminary AC check by professional servici ng

The servicing technician usually makes a first AC c heck before completing any operation on the system. When the CEP team car is in the garage for servicing, the professional makes a preliminary AC check. The goal of this check is to make a first diagnosis on the failure cause. After this preliminary check, the servicing technic ian indicates a first diagnostic with a cost estimate. The client is subsequently free to accep t or refuse the recommended actions.

This first check up could include:

 verification of the blown air temperature in the c abin,

 control of the compressor clutch,

 measurement of the low and high pressures (AC on),

 analysis of refrigerant using an electronic analyz er plugged on to the service valves,

 verification of the pressure inside the AC loop by pressing the HP or LP valves.

Figure 3.4 illustrates the actions made by the prof essionals before doing any operation on the system (actions done before giving any diagnosis).

Preliminary AC check (50 cases)

0 5 10 15 20 25 30 35 40 45

air
temperature Comp clutch HP LP Refrigerant
analysis Press

shraderNumber of cases

0%

10% 20% 30% 40% 50% 60% 70% 80% 90%Sample percentage

Figure 3.4 Preliminary AC check.



### 68% of professionals immediately check the blown ai r temperature in order to verify the availability of the fan and the coldness. two-thir ds of the professionals directly verify the compressor clutch by visualizing or by hearing that it is ON.

80% verify the low pressure and 76% verify the high pressure inside the system using a manifold when the AC is running. The difference between the two pressures in running mode (HP and LP) is an indirect way to check that the clutch is ON. In contrast, when the engine and the AC are OFF, the pressure check indicates if any refrig erant remains.

Other actions have been noted: the analysis of the refrigerant (7 cases), and pressing the Schrader valve in order to verify that refrigerant is released (6 cases). It should be mentioned that the preliminary AC check could combine two or more verification types.

After doing these preliminary checks, professionals give a first diagnosis (see Figure 3.5). The primary action recommended was a recharge of the AC system (94% representing 47 cases). InEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -45 - 

### 34 cases the advice given to the CEP team was to ch eck the leak tightness (68%). It should be noted that in only 76 percent of these cases was th e system checked for leaks.

Preliminary diagnostics and advices (50 cases)

0 5 10 15 20 25 30 35 40 45 50

Leak check recharge Change

compressor Buy SCNumber of cases

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Sample percentage

Figure 3.5 Preliminary diagnosis and recommendation s.



### Three particular cases should be mentioned: 2 garag es recommended the CEP team change the compressor (note: these two recommendations wer e made for the Mitsubishi), the third one recommended buying small cans from an auto-parts st ore and recharge the AC.



### 3.3.2 Leak search and recharge by professional se rvicing

Depending on the diagnosis and the estimate given b y the professional, the CEP team then has the choice to accept or decline the recommended act ions.

When the professional is requested to operate on th e vehicle, two evaluation steps are then performed. The first one is the leak search and th e second one is related to the charging procedure.

Leak search procedure evaluation

Among the 50 technicians met only 47 have operated on the system. The three other cases are those who advised the CEP team to change the compre ssor or to buy SC from an auto-parts

store.

First actions done (47 cases)

0 5 10 15 20 25 30 35 40 45

Evacuate to atmosphere

vaccum recharge Recover and

recycle vaccum recharge keep the initial

charge add refrigerant

to initial charge Add DYENumber of cases

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%Sample percentage

Figure 3.6 Small can users - Sample 1 description.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -46 - 

### The CEP team noted that four types of main first ac tions are performed when the servicing is accepted. These actions are classified as follows (see Figure 3.6):

 The technician releases the refrigerant to the atm osphere, evacuates the system and recharges it (4 cases)

 The technician recovers the refrigerant, recycles it with an automatic machine, evacuates the system, and recharges it partially or completel y (24 cases),

 The technician keeps the system untouched with the remaining charge (7 cases),

 The technician adds refrigerant to the remaining c harge done by CEP (13 cases).

Whatever the method of operation, 26 technicians am ong the 47 have added dye to the system using the automatic group or a special charging kit . In addition to the fact that those 26 technicians have added dye, some of them did not pe rform the leak check. In fact, those technicians requested the CEP team to come back lat er for a leak search with a fluorescent detector (20 cases).

Even though 34 technicians have recommended verifyi ng the leak tightness as a first diagnosis, only 26 have performed the leak check (see Figure 3 .7). In all cases, 5 methods are indicated:

 Controlling the rise of the vacuum pressure (7)

 Direct UV detection (22) including 3 technicians w ho noticed that the system is already charged with dye

 Later UV detection (20)

 Electronic detection (14)

 Pressurized air or CO 2 

### with soap bubble (2).

Leak search method (26 cases)



### 0 5 10 15 20 25 30

Control rising

vaccum

pressure Direct UV

detection Later UV

detection electronic

detection Pressurized

air or CO2 soap bubbleNumber of cases

0%

20% 40% 60% 80% 100%Sample percentage

Figure 3.7 Leak search methods.



### Note: Technicians who used soap bubbles to detect t he leak are those who filled the system with pressurized air or CO 2 

### . The technicians who used CO 2 

### proceeded later with a UV detection after releasing the CO 2 

### to the atmosphere, then charging with R-134a + DYE

.

Several methods could be combined in order to verif y the leak tightness of the system. When using an automatic charging machine, the pressure r ise after evacuation is easily controlledEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -47 - 

### (automatically). For UV detection, it is easier to add oil including dye. An electronic check could
be also done later. The leak search time is direct ly related to the good will of the professional who does the servicing. If he spends more time sea rching leaks, the probability of forgetting potential leaks decreases.

Two technicians performed a careful leak search, sp ending the necessary time for that. 13
technicians have done it in less than 10 minutes. The 11 others took from 10 to 20 minutes (see Figure 3.8).

Leak search time in minutes (26 cases)

0 5 10 15 20 25 30

t < 10 10 < t < 20 t > 20Number of cases

0% 20% 40% 60% 80% 100%Sample percentage

Figure 3.8 Leak searching time.



### Among the 26 technicians who did the leak search, 8 of them found leaks (see Figure 3.9). But the leaks found do not correspond to those detected by the CEP team at the TxV connection. In fact, most of the cases were traces of UV at severa l sites:

 4 leaks are detected at the service valves,

 3 leaks are detected at the suction line,

 1 leak on the condenser.

Leak detection (26 cases)

0 5 10 15 20 25 30

detect leak Do not detect a leak Check evaporator lea kNumber of cases

0% 20% 40% 60% 80% 100%Sample percentage

Figure 3.9 Leak detection.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -48 - 

### Concerning the three technicians who found a leak o n the suction line, one of them advised the CEP team to change the complete line, the second on e to change the seal of the fitting, while the third one who found a leak on the suction port of the compressor, advised the team to change the line and the compressor. Of course, the CEP team declined doing that. The 20 other professionals did not detect any leak. None of the professionals detected the leak at the
TxV.

It should be mentioned that 8 technicians verified the leak tightness of the evaporator by opening the evaporator box.

Recharge procedure evaluation

Among the 50 garages considered at the beginning, 4 0 have charged the system with refrigerant. The 10 others who did not charge the system made the following comments:

 1 technician said that the system was overfilled w ith oil (garage number 4)

 1 technician advised to buy a SC (garage number 7)

 3 garages number 8, 11, 48 have given only advice

 1 technician advised to buy a Schrader from an aut o-part store (garage number 9)

 2 technicians advised to change the compressor (ga rages number 22, 49)

 2 technicians detected the leak at the suction lin e. The first recommended changing the line, the other one to change the suction seal (gar ages number 43, 40).

Operation (50 cases)

0 5 10 15 20 25 30 35 40 45

Charge the system Did not charge the
system nominal charge

acknow ledge operation ID stickerNumber of cases

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%Sample percentage

Figure 3.10 Recharge procedure.



### Before charging the system with refrigerant, 34 tec hnicians read the nominal charge indicated by
the manufacturer under the hood. This information is crucial if the professional wants to exactly charge the system properly.

An important point has to be mentioned: only 4 prof essionals marked their operation by putting a sticker under the hood indicating the date of opera tion and the mass of refrigerant charged.

Three methods are used by professionals to charge t he refrigerant in the system according to the equipment available in their garage.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -49 - 

###  The use of an automatic machine successively doing the recovery and the recycling, the evacuation and the charge. 29 out of the 40 who di d the recharge used automatic
machines.

 The use of a refrigerant cylinder with a manifold and vacuum pump. 13 used this method but not all of them used the vacuum pump.

 The use of small cans to only charge the system, w ith neither recycling nor evacuation. In fact they only complete the charge (5).

Forty technicians performed the refrigerant charge (see Figure 3.11). Two of them made a complementary charge with small cans, the first usi ng an automatic charging machine and the other using the cylinder and manifold. The first u sed the small can because he wanted to add a stop leak (4 oz), the other one added oil (SC 12 oz + oil).

Charging method (40 cases)

0 5 10 15 20 25 30 35

Automatic machine cylinder + manifold Small canNumber of cases

0% 10% 20% 30% 40% 50% 60% 70% 80%Sample percentage

Figure 3.11 Charging methods.



### Twentysix technicians added dye when charging the s ystem. Twentyfour added oil to the system either by using an automatic machine or by i njecting the oil directly with a specific charging kit. 1 technician charged with a small ca n including a “stop leak” additive.

Additives (40 cases)

0 5 10 15 20 25 30

DYE Oil Stop leak with SCNumber of cases

0% 10% 20% 30% 40% 50% 60% 70%Sample percentage

Figure 3.12 Additives.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -50 - 

### In order to evaluate the refrigerant charges done b y the professionals and compare it to the original charge indicated by the manufacturer the C EP team analyzed the precise recovery of refrigerant from the MAC system after each visit.

The technicians who charged are classified into fou r groups (see Figure 3.13).

 In blue those who charged with an automatic machin e

 In green those who charged with a cylinder and a m anifold.

 In orange those who charged with small cans

 In red those who combined two methods

Note: the red line indicates the manufacturer nomin al charge of the vehicle (680 grams). The 2 peaks shown correspond to the 2 cases performed with the Cadillac.

0 100 200 300 400 500 600 700 800 900 1000131012151619202123242526272829303132343536373839414247131418334445462565017

Garage NumberRefrigerant charge (grams)

0 100 200 300 400 500 600 700 800 900 1000

Figure 3.13 Refrigerant charge recovered for all pr ofessionals.



### In Figure 3.13, the black dots represent those tech nicians that did not check the nominal refrigerant charge specified by the manufacturer. The first reason is the precision of the
automatic machine. The second reason is that some professionals do not respect the manufacturer charge even if they read it before.

Those technicians who charged with a cylinder/manif old combination did not use a scale to weigh the refrigerant charge.

Garage number 44 released the charge to the atmosph ere. Initially, the system was empty, so he charged the system without prior evacuation. Th e pressure increased when he ran the AC and the relief valve released the refrigerant. The same story occurred with garage number 46.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -51 - 

### The summary of operations and actions during the 50 visits are presented in Figure 3.15.

Interventions price

$0 $50 $100 $150 $200 $2501234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950

Garage numberPrice in USD

Figure 3.14 Prices as a function of garages and ope ration.

50

garages 47

first actions & diagnostics

3
diagnosis failure 18 recharge only 4

Leak search only

22

Leak search & recharge

3

advices 26

Leak search

40 Recharge

Figure 3.15 Operation summary.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -52 - 

### 4. Laboratory Testing

4.1 Evaluation of potential leak sources of profess ional servicing

The aim of this section of the study is to first ev aluate the potential leak sources of refrigerant while a professional is intervening on the AC syste m. The second purpose is to recommend a series of actions to be done in order to ensure pro per and less leaky maintenance.



### 4.1.1 System performances related to refrigerant ch arge

The cooling performance evolution of one of the 5 M AC systems studied in Section 1 is analyzed along a leaking process. A controlled slow leak is simulated when the MAC system is operating in a steady state regime. The tests are performed at the CEP laboratory using its MAC test bench (Photo 4.1).

Photo 4.1 General view of the test bench. Photo 4.2 Leak valve with micro counter.



### The leak is controlled using a micro-counter precis e valve (see Photo 4.2). The LFR is about 1.34 g/min. The leak is determined by weighting th e recovered refrigerant in a cylinder connected to the low-pressure service valve.

The leak process begins when the steady state regim e is reached: the leak valve is opened, the leak begins and continues until performance starts to decrease (very low cooling capacity, very high superheat, very low evaporating and condensing pressures). The leak test process takes place over 7 hours.

The system is charged at the beginning of the test with 700 grams of refrigerant. The mass of refrigerant, recovered 7 hours later, is 130 g.

The temperature is maintained at 30°C at the evapor ator inlet. The air temperature equilibrium at the condenser inlet is 33°C. Tests are performe d at 1000-rpm compressor speed; the air mass flows on the condenser and evaporator are resp ectively 420 and 1540 m 3 

### /h.

Figures 4.1 and 4.2 show respectively the condensin g pressure and the sub-cooling evolutions as a function of the refrigerant charge.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -53 - Condensating pressure evolution

0 200 400 600 800 1000 1200 1400 1600 1800 2000

100 200 300 400 500 600 700

Refrigerant charge [gr]Condensating pressure [kPa] Subcooling evolution

0 2 4 6 8 10 12 14 16 18 20

100 200 300 400 500 600 700

Refrigerant charge [gr]Subcooling [K]

Figure 4.1 Condensing pressure evolutions. Figure 4 .2 Sub-cooling evolutions.



### Figures 4.3, 4.4 and 4.5 show respectively the evap orating pressure, the superheat, and the supply air temperature evolutions as a function of the refrigerant charge.

Evaporating pressure evolution

200 220 240 260 280 300 320 340 360

100 200 300 400 500 600 700

Refrigerant charge [gr]Evaporating pressure [kPa] Superheat evolution

0 4 8 12 16 20 24 28 32 36

100 200 300 400 500 600 700

Refrigerant charge [gr]Superheat [K]

Figure 4.3 Evaporating pressure evolutions. Figure 4.4 Superheat evolutions.

Supply air temperature

8 10 12 14 16 18 20 22 24 26 28

100 200 300 400 500 600 700

Refrigerant charge [gr]Temperature [°C]

Figure 4.5 Blown air temperature evolutions at the

evaporator outlet.



### As seen in Figures 4.1 to 4.5 , three phases could be considered:

o The first phase corresponding to a system charge v arying from 700 to 520 grams

o The second phase corresponding to a system charge varying from 520 to 340 grams

o The third phase corresponding to a system charge v arying from 340 to 130 grams.

The first phase corresponds to the case where the l iquid receiver still contains refrigerant in liquid phase whatever the remaining quantity. In t his case, the system performance remainsEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -54 - 

### constant independent of the refrigerant quantity. All properties are unchanged, especially the cooling capacity.

The second phase corresponds to the case when there is no more liquid in the receiver, and that sub-cooling is fairly small. It has to be noticed that the sub-cooling decreases along the leaking process (see Figure 4.2), the superheat increases l inearly (see Figure 4.4), and the air temperature at the evaporator outlet increases slig htly (see Figure 4.5), meaning that the user or the mechanic cannot diagnose refrigerant loss under those temperature conditions.

The third phase is reached when the refrigerant cha rge is low. The heat exchangers are then oversized, and the condensing pressure decreases. The mass flow rate decreases at the TxV. The superheat and the air temperature at the evapor ator outlet increase rapidly. The temperature level indicates the need for refrigeran t recharge.

The system tested is equipped with a thermal expans ion valve (TxV) and a fixed displacement compressor working in a steady state regime. For M AC system equipped with an orifice tube expansion valve (OT), the variations of pressures a re more sensitive to the refrigerant charge, especially during the first phase.

Concerning the user, the only parameter to evaluate the system operation is the blown air temperature. According to Figure 4.5, no significa nt changes to the blown air temperature can be detected before losing about 50% of the refriger ant charge (340 grams).



### 4.1.2 Potential leak sources during a typical maint enance procedure

During a classic maintenance procedure performed by a technician, the potential emissions are
related to:

- connection and disconnection of the recovery equip ment to the service valve

- connection and disconnection of the charging cylin der or a small can

- rough verification of refrigerant charge by trigge ring the service valve

- direct evacuation of the MAC system without recove ry

- emissions, when dismounting a component, if the re covery procedure has not been accomplished properly. Significant emissions are due to direct evacuation and release of refrigerant from a small can, when not properly charged in the MAC system (the re maining quantity in the can, the “heel” is significant).

First operations done on the system before a leak s earch could be divided in four actions. According to Figure 3.15, the main action done is t he use of automated recovery machine, which recovers, recycles, evacuates, and recharges (48% o f the visited garages).

The second main action consists of adding refrigera nt to the initial charge usually using cylinder and manifold or small cans (24%).

The third case is to keep the initial charge when s earching the leak (14%).

The last case is the evacuation into the atmosphere in order to evacuate the refrigerant and recharge (8%).

Note: in the first case, all technicians have recov ered the refrigerant before making a leak search, which is clearly wrong because the driving force of the leak is the refrigerant pressure inside the MAC system. .Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -55 - 

### Service valves

In fact, each time the service valves are used a le ak occurs. The refrigerant quantity released is random and depends on the professional actions and equipment used. The leak is estimated usually in between 2 to 5g. Undue verification of refrigerant pressure by pushing the Schrader mechanism of the service valve may lead to emission s of up to 10 to 15 g.

When a professional connects the recovery equipment or cylinder using a quick coupler with moving rod, emissions are usually lower compared to connections fastened with a fixed rod. Photo 4.3 shows a quick coupler with a moving rod. When turning the valve, the rod moves to push the Schrader valve of the service valve. The leak tightness is assured before the Schrader is pushed down and to make the connection. In fact , these connections are connected first to the service valve and then the gates are screwed an d opened.

In contrast, the quick couplers with a fixed rod op en the gates at the moment they are connected. Photos 4.4, 4.5, and 4.6 show three typ es of quick coupler with fixed rod fastened with clips.

Photo 4.3 Quick coupler - Connection with moving rod by screwing fastened with clips. Photo 4.4 Quick coupler - connections with fixed ro d fastened with clips equipped with ball valve.

Photo 4.5 Quick coupler - connections with fixed

rod fastened with clips. Photo 4.6 Quick coupler - connections with fixed ro d fastened with clips.



### For couplers with a fixed rod, the tightness of the operation is random and dependent on the technician skills operating the system. If the Sch rader valve is pushed straight, the valve will leak less or not leak at all. In contrast, if the Schrader is wrongly pushed, it will leak unexpectedly.

Clearly, the couplers with moving rods leak less. The coupler is first fixed on the service valve, the valve is then turned in a way to move down the rod and open the gate. The professional could check the way the valve is installed before o pening the Schrader.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -56 - 

### The charging method

The charging method is a potential source of refrig erant leak. As shown in Section 3.2.2, professionals can use three methods to charge a MAC system:

- with automated machines (72.5%)

- with cylinder + manifold (20%)

- with small cans (7.5%).

Usually, the automated machines perform the whole procedure without action by the professional (recovery, evacuation, leak test, and recharge). The machine is connected to the system via HP and LP service valves. The quick couplers used are usually with a moving rod, allowing good leak tightness.
The connection between the machine and the system is set once.

Photo 4.7 Automated machine in service.



### The major emission occurs at the connection valves (assuming that the machine is tight enough). Each time a hose is installed or removed, a small emission occurs. For this reason,
the use of an automated machine leads to lower emis sions because there are only 2 connecting actions on the HP and LP pressure service valves, a nd 2 disconnecting actions, which constitute the smallest number of connecting / disconnecting a ctions.

Another conventional method consists of using successively:

- a recovery machine,

- a recovery cylinder,

- a manifold,

- a vacuum pump. So the possible number of connecting /disconnecting actions could be as high as ten, and thus refrigera nt emissions are higher.

Photo 4.8 Recovery machine and cylinder.


### Recovery efficiency and evacuation

Whatever the method used, the recovery machine allo ws recovering refrigerant at a specified limit (~4.3 psi absolute). The remaining refrigera nt in the system cannot be recovered and so it is released to the atmosphere when using the vacuum pump.

The vacuum pump releases the refrigerant or air rem aining in the system to the atmosphere. The remaining quantity of refrigerant depends on th e recovery pressure limit, temperature, and the system internal volume. Typically, this quanti ty varies from 10 to 100 g depending on the fixed low-pressure threshold.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -57 - 

### 4.1.3 Recommended service procedure

In fact, a user goes to a garage for MAC servicing in two cases: the AC system is working poorly or not working at all. The reasons for such malfun ctioning could be mechanical failure of the compressor or other components (evaporator blower, condenser fan, electronic command) or low refrigerant charge in the system. The professi onal should identify, by inspection, the source(s) of malfunctioning before connecting any h oses to the service valves.

As mentioned in the MACS (Mobile Air Conditioning S ociety) report on “recommended air conditioning inspection and preventive maintenance procedures”, the following steps have to be done leading to efficient and effective operation:

 Inspect the coldness of blowing air

 Inspect the compressor drive belt and clutch

 Inspect the flexible hoses and metal lines for sig ns of leakage or damage

 Inspect the compressor for signs of possible shaft seal leakage

 Inspect and clean the front of the condenser

 Check operation of all fans, blowers, air filters, and air circulation

 Check the functioning of the heater control valve (if any).

Once the mentioned actions are performed without an y observations indicating the cause of failure, the professional can then operate on the s ystem by measuring the pressure in order to confirm the presence of refrigerant.

1) AC OFF When the AC is OFF, the pressure at the equilibrium phase is related to the ambient temperature and not to the refrigerant charge. In contrast, with a single-phase presence the pressure is related to both: refrigerant charge and ambient temperature. When the pressure is lower than the saturation at the corresponding ambi ent temperature, that means the system is filled only with the gas phase. To conclude, when the AC is OFF the system pressure indicates

two cases:

 A partially empty system with gas phase (lower tha n saturation pressure or near atmospheric pressure).

 A partially or correctly filled systems if the pre ssure equals the saturation pressure.

So when the AC is OFF, the only conclusion that can be drawn from the value of internal pressure is associated with a nearly empty system ( without any more liquid). It cannot indicate the quantity of refrigerant when any liquid phase i s still in the system.

2) AC ON The measurement of evaporation and condensing press ures indicates the functioning of the compressor. Moreover, it could be useful to estima te the refrigerant charge in the system by comparing the thermodynamic properties as shown in Figures 4.1 to 4.5.

Note: the only way to acknowledge the correct charg e is to determine the sub-cooling:
Sb = T

outlet condenser



### – T sat 

### (condensing pressure) requires not only pressure m easurement but also precise temperature measurement at the condenser ou tlet.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -58 - 

### To conclude

 If the AC failure does not concern the refrigerant system (e.g. fan, air circulation, belt...etc), the professional should not operate on service valv es

 The first action concerning the refrigerant should be leak search before recovery

 If the preliminary tests are carried out, the prof essional could then operate on the service valves in order to check pressures in standstill an d in operation modes

 To recharge the system, the lowest emissions durin g servicing are obtained when using an automated machine with a quick coupler equipped wit h a moving rod

 The lower pressure threshold of the recovery machi ne pressostat has to be set as low as possible (typically 4.3 psi abs.); many are set jus t under atmospheric pressure (10 to 14 psi abs)

 For large leaks (> 40g/yr), the pressure raise aft er deep evacuation could be a correct method provided the oil is hot ( T > 50°C) in order to avoid refrigerant outgasing from the oil

 The leak search using either dye and UV lamp or el ectronic hand leak detectors are both acceptable methods (see Section 4.3), but only the wrapping method allows for detection of partial leaks in the range of 5 to 15 g/yr

 In the presence of a leak, the fluid is recovered in order to repair the leak. In the absence of a leak, the fluid is recovered and refilled with th e appropriate refrigerant charge.



### 4.2 Leak tightness tests of brand new and after use small cans

4.2.1 Introduction

The reference technique for DIYers to recharge a mo bile air-conditioning (MAC) system is to connect a small can to the system. The small cans are filled with refrigerant, currently HFC-134a, but may contain lubricant, dye, and seala nt. Both DIYers and professional
technicians use these small cans.

Section 4.2 is dedicated to the laboratory measurem ents of refrigerant emissions from small
cans before and after the first use.

The leak flow rate (LFR) is measured using an infra red spectrophotometer that continuously records the refrigerant concentration raise inside an accumulation volume where the can has
been installed. The test method is identical to th e one defined by the European Regulation
706/2007.

The leaks of 15 can samples have been measured befo re and after the first use, at three different temperatures making a total of 90 leak te sts. Tests have been performed at the CEP laboratory. Tests show that refrigerant emissions depend strongly on the can and charging kit sealing technologies.



### 4.2.2 Description of small cans

A small can consists of a sealed casing that contai ns a pressurized refrigerant that will be transferred to a MAC system by means of a valve and a flexible hose, the charging kit. This can is usually built by assembling three different meta llic parts: a jacket, a valve plate, and a bottom plate. The can leak tightness is achieved by placi ng an elastomer seal between the valve plate and the jacket, as well as a rolled edge seal on th e bottom plate (see Photo 4.9).Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -59 - Valve plate

Jacket

Bottom plate Elastomer seal

Rolled edge seal

Photo 4.9 Small can main components.



### The two families of small cans are defined by the v alve technology:

 A self-closing valve inserted in the valve plate ( type V, see Photo 4.10), or

 A valve, which is screwed and perforates the valve plate (type S&P, see Photo 4.12).

The charging kits also include a flexible hose conn ecting the small can to the air-conditioning system. The flexible hose and its low-pressure fit ting are not considered in this leak test study since they are free of refrigerant before and after a partial use.

The self-closing valve cans are available in 14 oz and 19 oz capacities. The self-closing valve is installed in the valve plate (see Photo 4.10) an d tightened with an elastomer seal (see Photo 4.11). An actuator pushes the stem downward (see P hoto 4.11) and the refrigerant is released to the flexible hose. When the user stops acting, the stem closes and the container remains
sealed.

Stem

Elastomer

seal Actuator

Photo 4.10 Valve plate with a self-closing valve. P hoto 4.11 Sectional view of a self-closing valve

actuator.



### The screwed and perforated cans have a different valve plate that incorporate s an externally threaded portion coupled with the valve plate (see Photo 4.12). This portion has a wall that will be penetrated by the pointer of a valve. The S&P c ans are available in different capacities: 12, 13, 14, and 18 oz.

Two different valve technologies can be found in S& P cans:

 the shut-off valve, and

 the push button valve.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -60 - 

### The shut-off valve is screwed on the can valve plate (see Photo 4.12) . After that, the user turns the handle and the pointer moves downward and penet rates the valve plate wall releasing the refrigerant. To isolate the container, the user mu st continue turning the handle until the pointer reaches the maximum displacement and contacts the v alve central body. Valve isolation is achieved by using an elastomer seal between the val ve and the container valve plate, and a metal-to-metal contact between the pointer and the valve central body (see Photo 4.13).

Handle

Pointer

Metal-to-metal

seal

Elastomer

seal

Photo 4.12 Valve plate of an S&P can. Photo 4.13 Se ctional view of a shut-off valve.



### The push button valve is also screwed on the can valve plate but has a d ifferent perforating
mechanism from the shut-off valve. As the user scr ews the valve, a pointer penetrates the valve plate wall and the refrigerant automatically flows to the valve. The valve is tightened by four different seals (see Photo 4.15). When the handle is squeezed, the refrigerant is transferred to the flexible hose and once the handle is released, the valve and the container are isolated.

Elastomer

seals

Handle

Photo 4.14 Rubber seal and pointer of a push button valve. Photo 4.15 Sectional view of a push button valve.



### The seal is the weakest link not only in the refrig erant container, but also in the charging kit. Seal performance depends on different variables, su ch as the surface topography, the seal material properties, the seal design, and the appli ed load. Accordingly, it is expected that, as the number of seals increase, the refrigerant emissions also increase.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -61 - 

### Tables 4.1 and 4.2 list a large variety of small ca ns and charging kits available on the California market, their type, content, market price, and on-l ine net price. A list of small cans and their characteristics are presented in Annex A.

Table 4.1 Details of tested small cans.

Brand Name Fitting type Capacity (g) Contents CEP
reference Notes

Interdynamics Valve equipped 510 R-134a + lubricant + leak
sealer C1-01 No rolled edge
seal

Interdynamics Valve equipped 510 R-134a + lubricant + leak
sealer C1-02 No rolled edge
seal Interdynamics Valve equipped 396 R-134a + lubricant C1-04

Interdynamics Valve equipped 397 R-134a + lubricant + leak
sealer C1-06

Interdynamics Valve equipped 398 R-134a + lubricant C1-07

Interdynamics S&P 396 R-134a + lubricant + leak
sealer C1-03

Interdynamics S&P 396 R-134a + lubricant C1-05

Interdynamics S&P 396 R-134a + lubricant + leak
sealer C1-08

Interdynamics S&P 398 R-134a + lubricant + leak
sealer C1-10

Interdynamics S&P 368 R-134a + lubricant + leak
sealer C1-13

Technical
Chemical Co S&P 340 R-134a C3-01

Technical
Chemical Co S&P 340 R-134a C3-02

Technical
Chemical Co S&P 340 R-134a + leak sealer C3-03

EF Products S&P 538 R-134a + lubricant + leak
sealer C4-01

EF Products S&P 538 R-134a + lubricant + leak
sealer C4-02Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -62 - Table 4.2 Details of tested charging kits. 

### CEP
reference Fitting type Photo

F1-01 Valve

equipped

F1-02 S&P
F1-03 S&P
F1-04 S&P

F1-05 S&P

F1-07 S&P

CEP
reference Fitting type Photo

F1-09 S&P

F1-11 S&P

F1-12 S&P

F1-13 S&P

F4-02 S&P

As indicated above, two series of tests have been p erformed on the two families of small cans: the first series on the brand new small cans, and t he second series after a first use of the small

cans.

The S&P cans are cheaper than those with valve or v alves plus a pressure gauge. The S&P price varies according to the refrigerant content a nd the brand name. For this reason, people prefer to buy the charging kit once and then re-use it with S&P cans. It has to be noticed that the S&Ps are dominant (nearly 90% of the market, as assessed by several dealers) for two reasons: the more knowledgeable DIYers buy S&Ps due to the easiness of use; less knowledgeable, but price-oriented DIYers are also c hoosing S&Ps. Users prefer to buy S&P cans since they are cheaper than valve-equipped one s and they can re-use the charging kit with
others S&P cans.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -63 - 

### 4.2.3 Tests and results

The aim of this section is to evaluate the can tigh tness, before and after partial use, in order to verify if the can is tight enough to keep the remai ning refrigerant in the can for a later use.

The CEP has developed a method for determining the annual leak flow rate for MVAC components using infrared spectro-photometry [ACE05]. This method o f testing is consistent with European regulation 706 / 2007 [EU706]. The leak flow rate of a can is measured in an accumulation volume (see Photo 4.16) by an infrared spectrophotometer. The raise of
R-134a concentration is measured in the accumulatio n volume and translated into annual mass leak flow ra te.

Photo 4.16 Accumulation volume where refrigerant annual leak is

measured



### Before leak tests, the infrared gas analyzer is cal ibrated using three different refrigerant concentrations: 0, 100, and 450 ppm. The cell volu me is calculated using a calibrated leak (see Figure 4.6). The LFR measurement relative uncertai nty is about 6%.

Cell volume calibration Leak@21 °C = 47,8 g/yr

0 20 40 60 80 100 120 140 160 180 200

0.0 0.3 0.5 0.8 1.0 1.3 1.5

Time (hr)HFC-134a concentration (ppm)

Figure 4.6 Refrigerant concentration raise using a calibrated leak.



### As shown in Photo 4.16, the can is installed inside a hermetical volume where ambient pressure and temperature are controlled. Measurement starts when the preset temperature is reached. The annual leak flow rate is calculated using only the linear evolution of the refrigerant
concentration.

The measurement accuracy is better then 0.1 g/yr.

As shown in Table 4.3, tests have been performed on S&Ps as well as on valve-equipped cans.
The leak flow rates are determined before and after the use of cans. An S&P type can is considered new when the can tap of the charging kit is not screwed on it. A valve-equipped type can is considered new when it is intact as purchase d.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -64 - Table 4.3 Small can leak test results.

Net Weight [g] Type CEP Reference new used
°C °C

30 35 40 30 35 40 Charging Kit

**Ezchill 510**  **V C1-01**  **3.17 3.88**  **5.28 3.41**  **4.05 4.79**  **F1-01**

**Ezchill 396**  **S&P C1-03**  **0.11 0.19**  **0.32 0.19**  **0.28 0.55**  **F1-02**

**Ezchill 510**  **V C1-02**  **0.83 1.24**  **1.95 0.86**  **1.24 1.65**  **F1-01 Ezcharge**  **396 V**  **C1-04 0.62**  **1.03 1.73**  **0.55 0.86**  **1.51 F1-01** 

**Ezchill 396**  **S&P C1-05**  **0.37 0.60**  **1.05 441**  **526 714**  **F1-09**

**Ezchill 397**  **V C1-06**  **0.97 1.59**  **2.27 0.70**  **2.08 3.34**  **F1-01**

**Ezchill 398**  **V C1-07**  **0.66 1.09**  **1.64 0.75**  **1.14 1.84**  **F1-01**

**Artic 396**  **S&P C1-08**  **0.39 0.62**  **0.97 1.52**  **2.23 2.60**  **F1-12**

**Artic 398**  **S&P C1-10**  **0.41 0.62**  **1.09 3.09**  **4.48 5.86**  **F1-11 High Mileage**  **368 S&P**  **C1-13 0.33**  **0.49 0.77**  **0.41 0.62**  **1.06 F1-04** 

**Johnsen's 340**  **S&P C3-01**  **0.02 0.04**  **0.03 139**  **298 604**  **F1-13 Johnsen's**  **340 S&P**  **C3-02 0.004**  **0.005 0.01**  **37.0 50.1**  **67.8 F1-07**  **Johnsen's 340**  **S&P C3-03**  **0.004 0.008**  **0.01 0.02**  **0.03 0.05**  **F1-05**

**Sub-zero 538**  **S&P C4-01**  **0.04 0.05**  **0.08 0.04**  **0.05 0.08**  **F4-02**

**Sub-zero 538**  **S&P C4-02**  **0.05 0.07**  **0.11 0.06**  **0.11 0.19**  **F1-03** 

### Leak Flow Rate [g/yr]

**Technical Chemial Co,** Interdynamics

**EF Products** Brand name 

### Small Can

Leak tests on V-type small cans For the valve-equipped cans (V-type), emissions are always slightly higher compared to S&Ps and in one case significantly higher (3.2 g/yr at 3 0°C). Values measured before and after can usage are of the same order of magnitude.

All cans are brand new and when the tests are made before use, the test is labeled Brand New (BN). Five of the V-type small cans have been test ed. These cans are all manufactured by Interdynamics. Since the self-closing valve is ins talled on the can, the charging kit does not contribute to refrigerant emissions before and afte r a partial use.

Refrigerant emissions for new valve equipped cans a re presented in Figure 4.7. As the leak flow rate and the saturation pressure are related in a q uadratic relation, it is obvious that the leak flow rate increases with temperature. Refrigerant emiss ions from the C1-01 can are three times higher than the other valve-equipped cans and lower than 6 g/yr.

The second series of tests performed after the firs t use of the five V-type small cans were labeled After Use (AU). As shown in Photo 4.13, th e actuator only pushes the stem downward and, when released, a spring pushes the stem and cl oses the container. This means that changes on emissions after use could only be relate d to the rubber seal that moves with the stem. Figure 4.8 shows the variation of the leak f low rate after the first use is never higher than 1 g/yr and, for the C1-01 can, it is 0.5 g/yr lower than a new can.

Leak flow rate (LFR) for new valve-equipped cans

0 1 2 3 4 5 6LFR (g/yr)

30 °C 3.17 0.83 0.62 0.97 0.66

40 °C 3.88 1.24 1.03 1.59 1.09

50 °C 5.28 1.95 1.73 2.27 1.64

C1-01 C1-02 C1-04 C1-06 C1-07 Delta leak flow rate (LFR) after a partial use

-0.5 0.0 0.5 1.0 1.5LFR (g/yr)

30 °C 0.24 0.03 -0.07 -0.27 0.09

40 °C 0.17 0.00 -0.17 0.49 0.05

50 °C -0.49 -0.30 -0.22 1.07 0.20

C1-01 C1-02 C1-04 C1-06 C1-07

Figure 4.7 Leak test results of new V-type cans

(BN). Figure 4.8 Leak test results of V-type cans (AU).Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -65 - 

### Leak tests on type S&P small cans

Five brand new S&P small cans have been tested. Th e leak test results for BN S&P small cans illustrates an important difference among the three different manufacturers that have been tested (see Figure 4.9). S&P small cans from manufacturer C1 , are significantly more emissive than
the C4 and C3 ones. For the same container pressure and type, w e found refrigerant emissions
from C1 cans 100 times higher than that of the C3 and C4 ones.

Leak flow rate (LFR) for new S&P cans

0.0 0.2 0.4 0.6 0.8 1.0 1.2LFR (g/yr)

30 °C 0.11 0.37 0.39 0.41 0.33 0.02 0.004 0.004 0.04 0.05

40 °C 0.19 0.60 0.62 0.62 0.49 0.04 0.005 0.008 0.05 0.07

50 °C 0.32 1.05 0.97 1.09 0.77 0.03 0.01 0.01 0.08 0.11

C1-03 C1-05 C1-08 C1-10 C1-13 C3-01 C3-02 C3-03 C4-01 C4-02

Figure 4.9 Leak flow rate test results of S&P cans (BN).



### These five S&P cans have been perforated for the fi rst use and re-tested to evaluate the valve technology impact on the refrigerant emissions (see Table 4.2). These test results are presented in Figures 4.10 and 4.11.

From the test results, it can be concluded that the push button charging kit technology is much
more emissive than the shut-off valve. The lowest leak flow rate value obtained for the push button valve is about 1 g/yr and the highest one is about 700 g/yr, which proves the leak prone behavior of this technology.

The leak flow rates of S&P cans, after use, depend on the type of charging kit used. The leak flow rate of the F1-02 charging kit is quasi simila r to the one of a new S&P can. In contrast, the F1-13 charging kit presents very high LFR (139 g/yr at 30°C) as well as F1-09, with annual LFR of 441 g/yr. F1-07 is neither satisfactory with 37 g/yr at 30°C. Of course, all charging kits where the refrigerant release is higher than 3 g/yr will quickly lead to an empty can.

Delta Leak flow rate (LFR) due to push button charg ing kit for S&P

cans

0 100 200 300 400 500 600 700 800LFR (g/yr)

30 °C 440.63 1.13 2.68 139.38 37.00

40 °C 525.20 1.61 3.86 298.16 50.10

50 °C 712.45 1.63 4.77 604.17 67.80

F1-09 F1-12 F1-11 F1-13 F1-07 Delta Leak flow rate (LFR) due to shut-off valve ch arging kit in S&P

cans

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35LFR (g/yr)

30 °C 0.08 0.08 0.02 0.00 0.01

40 °C 0.09 0.13 0.02 0.00 0.04

50 °C 0.23 0.29 0.04 0.00 0.08

F1-02 F1-04 F1-05 F4-02 F1-03

Figure 4.10 Test result of the push button

charging valve (AU). Figure 4.11 Test result of the shut-off charging valve (AU).Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -66 - 

### It can be concluded that some charging kits cannot be used on S&P cans after a partial charge, leading to a complete loss of the remaining refrige rant. Moreover, when using F1-13 charging kits during operation the CEP technician noticed si gnificant emissions.

When using the charging kit F1-09 at 30°C, the annual leak flow rate exceeds 400 g/yr , meaning that the refrigerant container will be empty in a f ew days. If a user chooses to use a shut-off valve and close it after the re-charging process, t he increase in refrigerant losses could be neglected.

The shut-off valve technology slightly impacts refr igerant emissions and, for the charging kit F4-
02 , has no impact at all. The high performance of th e shut-off valve is related not only to the use of just two seals, but also to the applied load in both seals. One of them is metal-to-metal (see Photo 4.12).



### 4.2.4 Conclusions

Based on the 90 leak tests presented above, refrige rant emissions from small cans before and after a partial use could be significant and depend strongly on the container and charging kit technology.

Two different small can technologies have been test ed: the V-type and the S&P type. As expected, S&P small cans before use show lower emis sions compared to V-type small cans. Particularly, the S&P coming from the brand name C3 shows the lowest emission level, which is nearly nil (see Figures 4.7 and 4.9). This means t hat, when stored in the sales store, the S&P type small cans leak less than the V-type ones.

The charging kits are adapted to the container type . For valve-equipped cans, the charging kit does not modify refrigerant emissions. Therefore, they present almost the same emission level after a partial use (see Figure 4.8).

Two different charging valves have been tested for S&P type cans. The push button type has highly irregular emission behavior and an increase of 712 g/yr has been measured at 50°C (see Figure 4.10). The shut-off valve has been tested i n the same conditions and presents emissions lower than 0.3 g/yr (see Figure 4.11). It has to b e noticed that the S&P cans with a push-button charging kit and the valve-equipped cans have a sel f-closing system that prevents the user from emptying the container in a few seconds.

In order to reduce refrigerant emissions before and after the re-charging process, appropriate cans and charging kits have to be chosen. These te st results suggest the use of S&P cans with a shut-off valve charging kit will minimize HFC-134 a emissions.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -67 - 

### 4.3 Sensitivity of Different Leak Search Methods

4.3.1 Introduction

In order to determine the effectiveness of the leak search methods, a comparative study of leak sensitivity to: dye, electronic leak detectors, and the soap bubble method was carried out, using the infrared spectroscope to measure exactly the LF R that can be detected by each method.

Five fittings with the same design and different LFRs have been chosen (see Photo 4.17). They are composed of two flanges and one o-ring seal, and put together with a screw.

Photo 4.17 Fittings technology used for this compar ative study.



### 4.3.2 Test procedure

First, each fitting has been put under pressure wit h HFC-134a and installed inside an accumulation volume to be leak tested using an infr ared spectrophotometer (IS). Refrigerant pressure is set to 770 kPa and the fitting temperat ure to 35°C, superheated to 5°C to avoid refrigerant condensation inside the component. Thi s leak test is the same as the one described
for the small can leak tests. This first test is f ollowed by a leak search using an Electronic Leak Detector (ELD) and a Soap Bubbles (SB) test.

The ELD leak detection is achieved by placing the s niffer as close as possible of the component and then moving slowly all around the flanges junct ion. If the leak detector audible alarm intensifies, then the leak is considered as detecte d. Before the leak search, the ELD is checked with a calibrated leak of 6 g/yr (see Photo 4.18).

Photo 4.18 Calibrated leak for checking the ELD. Ph oto 4.19 Leak detection with Electronic Leak
Detector.



### The SB leak detection is achieved by spraying the f langes junction with a soap solution. If the formation of bubbles is visible to the naked eye, t hen the leak is considered detected.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -68 - Photo 4.20 Leak detection with DYE Photo 4.21 Leak detection with Soap Bubble (1200 g/yr).



### The refrigerant LFR measured for Samples 4 to 6 hav e been performed before the dye
visualization.

Second, without disassembling the flanges, fittings have been charged with refrigerant HFC-134a, PAG lubricating oil, and dye. The refrig erant pressure is set to 770 kPa and the fitting temperature to 35°C. Then, they have been observed with a fluorescent light to determine the time taken by the refrigerant, oil, and dye to go through the leaky seal (see Photo 4.19). Once the test has led to positive detection, the re frigerant LFR is measured with the infrared spectrophotometer. Third, the ELD and the SB techn iques are also tested (see Photos 4.20 and 4.21).



### 4.3.3 Leak test results and conclusions

When comparing Tables 4.4 and 4.5, the fittings bei ng in the same conditions, the lubrication effect is very significant especially for high LFRs . For example, for fitting no. 1, the lubrication of the fitting results in reducing the LFR from 662,00 0 g/yr to 14.7 g/yr, and for Sample no. 2 from 1,490 to 120. This effect is systematic even if no general law can be derived from those tests. Lubrication of all fittings leads to significant im provement of leak tightness.

For dry contact, only ELD and SB can be used becaus e dye is diluted in the oil. As it can be seen in Table 4.4, the practical limit of detection has been 7.2 g/yr for both ELD and SB.

Table 4.4 LFRs of fittings with dry contact.

1 st leak test - Dry contact

Test method Sample IS [g/yr] ELD SB

No.1 662,000 Detected Detected No.2 1,490 Detected Detected

No.3 515 Detected Detected

No.6 300 Detected Detected

No.4 7.2 Not detected Not detected

No.5 0.28 Not detected Not detected



### For the second series of tests with lubricated join ts, strangely enough the threshold detection has been different and even a LFR of 14.7 g/yr has not been detected either by ELD or SB but has been detected by dye.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -69 - 

### When comparing Samples 1, 2, and 3, it can be deduc ed that the lower the LFR, the longer the time the dye has to go through the leaky fitting. Sample 3 seems to indicate that a leak as low as 5.7 g/yr can be detected by dye only after 11 ho urs, this leak was not detected either by ELB
or SB.

Table 4.5 LFRs of fittings with lubricated contact.

2 nd leak test - Lubricated contact

Test method Sample IS [g/yr] ELD SB DYE [hr]

No.1 14.7 Not detected Not detected 3

No.2 120 Detected Detected** 0.8

No.3 5.7 Not detected Not detected 11

No.6 0.7 Not detected Not detected ***

No.4 0.05 Not detected Not detected *

No.5 0.05 Not detected Not detected * *No evidence of DYE after 21 days of test ** Very small bubbles ***No evidence of DYE after 15 days of test



### After a 21-day test, no evidence of dye has been no ticed for Samples 4 and 5.

For Sample 2 (14.7 g/yr with a lubricated contact), the SB method has generated very small bubbles, which are very difficult to visualize.

It has to be noticed that in ELD and SB leak test m ethods, the leak search strongly depends on the leaky component accessibility. If fittings are not fully accessible, the leak visualization or location can be very hard to find. For the compres sor shaft seal, the refrigerating system most leaky seal, detection using ELD and SB methods is i mpossible because the clutch assembly
hides the shaft seal.

In conclusion, adding dye to the oil seems to be a simple and efficient way to detect leaks in the very busy environment under the vehicle hood. Thos e first tests do not indicate a significant advantage of usual methods (ELD or SB) compared to the use of dye.

The detailed fitting emissions are presented in App endix A.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -70 - 

### Appendix A: detailed fitting emissions

Fitting No.1 : Dry contact Fitting No.1 : Lubricate d contact

Fitting No.2 : Dry contact Fitting No.2 : Lubricate d contact

Fitting No.3 : Dry contact Fitting No.3 : Lubricate d contact

Fitting No.4 : Dry contact Fitting No.4 : Lubricate d contactEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -71 -

Fitting No.5 : Dry contact Fitting No.5 : Lubricate d contact

Fitting No.6_Dry contact
P = 770 kPa; T = 35 °C

LFR = 300 g/yr

0 25 50 75 100 125 150

0,0 0,1 0,2 0,3 0,4 0,5
Time (hr)Q(moleE-6) Fitting No.6_DYE+Oil
P = 770 kPa; T = 35 °C

LFR = 0,7 g/yr

0 2 4 6 8 10

0 2 4 6 8 10 12 14
Time (hr)Q(moleE-6)

Fitting No.6 : Dry contact Fitting No.6 : Lubricate d contact



### 5. Evaluation of the sales of HFC-134a disposable c ans in California

Two sources are available to evaluate the number of small cans sold in California. Based on the 2006 CARB consumer project survey, the number of HF C-134a small cans sold in California is close to 2 million cans per year equivalent to 0.85 MMT CO 2 

### equivalent per year. This data has been presented by CARB at the Scottsdale SAE Confer ence 2008 [ZHA08].

In 2005, E. Hoffpauir of MACS presented the refrigerant sales of HFC-134a for servicing and for new vehicles, as shown in Figure 5.1. So if California represents 10% of the U.S. small can sales (which is a typical assumption), the equivalent CO 2 

### is higher, in the range of 1.3 MMT CO 2 

### equivalent. In any case, the order of magnitude of direct emissions is in the range of 0.33 MMT CO 2 

### equivalent per year due to emissions during servicing by DIYers. Figure 5.1 HFC refrigerant sales for MAC systems - 2003 [HOF05].Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -72 - 

### 6. Summary, conclusions, and recommendations

The primary purpose of this project was to provide data for the regulatory development of a discrete early action under AB 32, the California G lobal Warming Solutions Act of 2006. The purpose of the regulatory measure was to reduce the emissions of high-GWP refrigerants during the re-charging of MVACs by DIY individuals. CEP s taff also performed a field study of MVAC servicing by professional technicians in order to e valuate the procedures followed in professional servicing and repair. Additional data was generate d which may be helpful in the development of other proposed regulations concerned with the emiss ion reduction of high-GWP refrigerants from MVAC systems.

The CEP staff performed two field studies including measurements of refrigerant emissions from the DIY re-charging of MVAC systems in the field. T he first field study focused on analyzing approximately 50 Do-It-Yourself (DIY) recharges on auto A/C units using from one or more small containers of automotive refrigerant. Through the measurements of refrigerant masses in the MVAC system and the container, the CEP staff calcul ated refrigerant emissions and their components during the DIY re-charging procedure. T he second field study was a qualitative study of the diagnostic and servicing practices of professional A/C servicing facilities when an MVAC system is significantly undercharged.

In addition, laboratory tests were conducted to dem onstrate: (1) how much refrigerant would be lost before the cooling performance of a selected M VAC began to deteriorate significantly, (2) a comparison of the sensitivity of different methods of leak detection, (3) the typical leak flow rates from “small cans” and their charging apparatus, and (4) the typical leak flow rate of the MVAC systems in the five most popular cars in California

.


### Refrigerant Emissions from DIY MVAC Re-Charging

Based on the field testing with DIY volunteers, two-thirds of the “small container” refrigerant is charged into the MAC system while 1/3 is emitted to the atmosphere. See the figure on the right. Almost 80 percent of the volunteers chose the S&P type cans because they already have the charging assembly and it is cheaper. It is also important to note that a small number of DIYers was responsible for the majority of the emissions. 43 percent of the operations resulted in 78 percent of the emissions indicating the need for proper training. Leak flow rate (LFR) for new valve-equipped cans

0 1 2 3 4 5 6LFR (g/yr)

30 °C 3.17 0.83 0.62 0.97 0.66

40 °C 3.88 1.24 1.03 1.59 1.09

50 °C 5.28 1.95 1.73 2.27 1.64

C1-01 C1-02 C1-04 C1-06 C1-07

Figure a – Components of a DIY Refrigerant Charge.



### The main drawbacks associated with non-professional servicing are: (1) DIYers not knowing the amount of refrigerant re maining in the system or the manufacturers’ specified charge, (2) MVAC system leak search and r epair are not conducted, (3) DIYers not recovering the refrigerant from the MVAC system pri or to re-charging, and (4) incorrect
instructions on the container labels.

Recommendations : For the DIY practice to be effective the use of the pressure gauge in recharging the MVAC should be discontinued because it is not a proper indicator of the level of the system refrigerant charge. In addition, the follow ing instructions need to be included on theEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -73 - 

### container label: (1) the engine must be running, (2 ) set the A/C system to maximum cooling with the fan on high, (3) an explanation of the can shak ing procedure to achieve a properly charged system, and (4) an explanation for determining when a container is empty. This last instruction would include minimal liquid movement from inside t he shaken container and a temperature rise
of the container.

Emissions from Small Containers

There are two types of small containers available o n the market: the screw-and-perforate (S&P) and the valve-equipped (V). According to the labor atory leakage measurements, new S&P type containers have an insignificant advantage over the V type containers prior to their use in recharging a MVAC.

After use, the V type containers showed little diff erence in leak rate when compared with the new V type containers prior to use. Leak rate meas urements were also carried out on S&P type cans with different charging assemblies installed. In two of the five cases, the kit equipped with the “push-button type” assembly resulted in emissio n increases of greater than 100 g/yr after use. In addition, this type of charging assembly r eleased refrigerant during the re-charging process. In comparison, all charging assemblies wi th the shut-off valve increased refrigerant emissions by less than 0.3 g/yr after opening and c losing the valves.

Recommendation : Prior to use, the leak rates from both V type and S&P type containers are very low. However, the design of the charging valv e and hose assembly and its interface with the S&P type container may have a significant effec t on the emissions from the small containers of automotive refrigerant. The “push-button” type charging kits for the S&P type cans should either be banned or re-designed to reduce refrigera nt emissions during and after usage.



### Professional Servicing

CEP staff conducted a field survey of professional A/C shops by taking in a vehicle with an intentionally under-charged MVAC to observe the pro cedures that the technicians followed and their diagnosis of the system performance.

The first check ups included: (1) verification of the air temperature coming out of the vents in the cabin, (2) actuation of the compressor clutch, (3) measurement of the low and high pressures with the A/C on, (4) identification of the refrigerant in the system using an electronic analyzer, and (5) verification of the pressure inside the A/C loop by pressing the HP or LP Schrader valves. The figure to the right shows the frequency of the different types of checks done by the professional
technicians. Note that DIYers as well as professionals check the ventilation air temperature while the other checks require the expertise and equipment of a professional
technician. Preliminary AC check (50 cases)

0 5 10 15 20 25 30 35 40 45

air
temperature Comp clutch HP LP Refrigerant analysis Press

shraderNumber of cases

0%

10% 20% 30% 40% 50% 60% 70% 80% 90%Sample percentage

Figure b: Method of diagnosis of the sample of

professionalsEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -74 - 

### Followed by the system checks, the technicians diag nosed the system problems and recommended a course of action which consisted prim arily of re-charging the MVAC system with refrigerant in over 90 percent of the cases. In al most 70 percent of the cases, the technician
recommended that a leak search be carried out altho ugh this was only done in approximately 75 percent of these cases. There is some degree of va riation in the check-up, diagnosis and recommendations performed by the technicians.

Professional Servicing with Recovery and Recharge M achines About two-thirds of the professionals used automate d recovery and recharge machines. This equipment is essential for limiting refrigerant emi ssions during servicing, provided the recovery is performed down to an absolute pressure of 4 psia. It was also observed that few professionals verify the refrigerant charge specified by the car manufacturer.

Different types of couplings are used in connecting the recovery and recharge machines to the MVAC systems. The usage of certain types of these couplings results in lower emissions of refrigerant. Standard testing should be performed on all couplings with the results published in order to promote the use of the ones with lower emi ssions.

Many fully automated recovery machines evacuate aft er recovery. A significant amount of refrigerant may be released during the evacuation p rocess because if recovery stops at an absolute pressure around 14 psia. These emissions could be reduced by continuing recovery until a lower pressure is reached.

Recommendations: All professionals should use recovery and recharge machines in servicing MVAC systems. The professional technician should m ake a systematic leak search before refrigerant recovery when the saturating pressure i s measured in the MAC system. When performing an A/C service, the technician should en sure that the manufacturers’ specified refrigerant charge is used and, upon completion of the service, a tag or sticker should be placed under the hood indicating the date of service. The low-pressure threshold for refrigerant recovery should be set at 4 psia so that more refri gerant is recovered from the MVAC system.



### Professional Leak Search Twentysix technicians performed the leak check usin g the following methods: (1) controlling the pressure rise after evacuation, (2) detection of UV-sensitive dye in the refrigerant, (3) using an electronic leak detector, and (4) the inspection for soap bubbles on a pressurized MVAC system. The majority of the techn icians used the detection of UV dye with the electronic leak detector being used to a lesser degree.

The UV dye method is the only one that can be perfo rmed by the non-professional, because the other techniques require a professional’s expertise and equipment. It should be noted that none of the technicians who participated in the study we re able to detect a refrigerant leak even though CEP staff was aware of a very small leak at the expansion valve. The observations on professional leak detection concerning the necessar y time lag between charging the dye and making a possible diagnosis of a leak is confirmed by laboratory tests which are described
below.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -75 - 

### The comparison of three detection methods at the CEP laboratory shows that the usage of a fluorescen t lamp with UV dye is comparable or superior to eithe r an electronic leak detector or the use of a soap solution on a pressurized MVAC system with an inspection for bubbles. The UV dye method has the capability of detecting a leak flow rate as low as approximately 6 g/yr after 11 hours.

Recommendation : A UV dye should be included in the refrigerant when the MVAC is charged during vehicle manufacture. This would give service technicians a simple means of identifying leaks. Figure c: Visualization of leak by UV dye.



### Costs of Professional and Non-Professional Servicin g

From the survey of professional shops, the cost for diagnosing a MVAC problem ranges from no charge to $20. For a professional diagnosis and re -charging with a recovery and re-charge machine, the cost ranges from approximately $50 to a little over $200. This may or may not include a leak inspection depending on the shop. I f the professional shop performs a diagnosis and a recharge using small containers or a bottle o f refrigerant, then the cost is under $100 according the shops that were checked. It should b e noted that only a small number of professionals gave a diagnosis or incorrect recomme ndations concerning the servicing/repair of the MVAC. For non-professional servicing/re-charge , the cost of the refrigerant container and the charging assembly may range from $15 to $40 dep ending on the circumstances. The nonprofessional servicing may provide a major cost sav ings for the consumer if the only problem is a low-refrigerant charge.

However, it should be remembered that professional servicing does provide an added value over non-professional servicing. Professional technicia ns specialize in servicing/repairing MVAC systems and possess the expertise and equipment to effectively perform their duties. The potential added values include: (1) correct diagnos is of failure, (2) effective leak search, (3) use of a recovery & recharge machine, and (4) capabilit y of repair.

Leak Rates from New MVAC Systems

The annual leak flow rates (LFRs) of MAC systems of the five most sold cars in California have been measured according to the methodology defined in the EU regulation 706/2007. The initial annual leak flow rates of those five MAC systems ar e of the same order of magnitude as those measured on European and Japanese cars. The averag e annual LFR of new systems is in the range of 10 g/yr ±4

. MVAC systems with double evaporator systems may hav e higher leak rates because of the extra connections, although tw o of the tested systems did have double evaporators.

Additional testing was conducted on one of the MAC systems. The system was mounted on a test bench, running continuously over 7 hours with a fixed leak rate of 1.5 g/min. Cooling performance data indicated that about 50% of the re frigerant charge has to be lost before the system ceases to perform adequately.

Recommendations:

The refrigeration circuit of MAC systems should no t require any servicing during the first 7 years because “regular” leaks ar e low unless there is some sort of catastrophic failure in the system. It is recommended that addi tional research work be conducted in order toEvaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -76 - 

### analyze the wear and degradation of compressor shaf t seals over time. This would lead to a greater understanding of why and when MAC systems b ecome significantly more emissive.



### An Alternative Approach for Do-It-Yourself MVAC Ser vicing

In re-charging a MVAC with a small container, the D IYer connects the charging hose assembly to the small ca n and the low-pressure service valve and shakes the c an while charging the system until the can feels empty

.

In using an automated R&R machine, an individual would connect the blue hose to the low-pressure ser vice valve, connect the red hose to high-pressure servic e valve, push the button, and return approximately ha lf anhour later after the completion of recovery and recharge.

If you compare these two procedures, the use of an automated machine is simpler. Figure d: Automated Recovery and recharge machine.



### It would be possible to allow DIYers to continue re charging their MVAC systems without using the small containers of automotive refrigerant. In stead of buying small cans, DIYers could rent the use of a recovery & recharge machine at an auto -parts retailer. This approach would be similar to an individual inflating the tires on his automobile. A person does not buy a compressor to do this operation but typically goes to a gasoli ne service station. In addition, a DIYer could perform a leak check on his MVAC by renting a UV la mp from the auto-parts retailer. This would be a relatively simple process If UV dye is include d with the refrigerant charge at the factory when the vehicle is being manufactured. The dye co uld also be injected by either a professional or a DIYer using a small can with dye.

Recommendations : Instead of using small containers to perform non- professional servicing, the DIYer should use a recovery & recharge machine that would be rented at auto-part stores. DIY individuals should perform leak checks on their sys tems. This would be feasible by charging refrigerant with UV dye at the factory, and auto-pa rts stores offering UV lamps for rent. In the interim, dye can be charged either by professionals or non-professionals.Evaluation of the Potential Impact of Emissions of HFC-134a From Non Professional Servicing of Motor V ehicle Air

Conditioning Systems – Final Report – December 2008 -77 - 

### References

[ACE05] Clodic, Denis, Yu, Yingzhong. Research stud y on the definition of the implementation

of a method of measurement of annual leak flow rate s (LFRs) of MAC systems. Report pour ACEA. January 2006. [CLO06] D. Clodic, Y. Yu. 2005. Research study on t he definition of the implementation of a

method of measurement of annual leak flow rates (LF Rs) of MAC systems. Report for ACEA. January 2006. [EUD06] Directive 2006/40/CE du Parlement européen et du Conseil du 17 mai 2006

concernant les émissions provenant des systèmes de climatisation des véhicules à
moteur et modifiant la directive 70/156/CE du Conse il. [EUR07] Règlement (CE) n° 706/2007 de la Commission du 21 juin 2007 établissant

conformément à la directive 2006/40/CE du Parlement européen et du Conseil les dispositions administratives relatives à la récepti on CE des véhicules ainsi qu'un essai harmonisé pour mesurer les fuites de certains systèmes de climatisation. [EU07] Commission regulation (EC) No 706/2007 of Ju ne 2007 laying down, pursuant to

Directive 2006/40/EC of the European Parliament and of the Council, administrative provisions for the EC-type-approval of vehicles, an d a harmonized test for measuring leakages from certain air conditioning systems. [HOF05] Elvis Hoffpauir. 2005. Reducing Refrigeran t Emissions at Service and Vehicle End of

Life. MAC Summit 2005. Sacramento, California. [ZHA08] Tao Zhan et al. 2008. Greenhouse Gas Emiss ions and Abatement Opportunities in

Do-it-Yourself Recharging of Leaky Motor Vehicle Ai r Conditioning Systems in California. SAE Congress, Scottsdale, Arizona.



### Abbreviations and acronyms

Abbreviations AC Air conditioning DIYer Do-it-yourselfer
ELD Electronic leak detector HFC Hydrofluorocarbons HP High pressure IS Infrared spectrophotometer
LFR Leak flow rate LP Low pressure MAC Mobile air conditioning MACS Mobile air-conditioning system MVAC Motor vehicle air conditioning
OT Orifice tube S&P Screwed & perforated SB Soap and bubbles
SC Small can
SCU Small can user SUV Sport utility vehicle TxV Thermostatic expansion valve
UV Ultraviolet

Acronyms
CARB Californian Air Resources Board CEP Center for Energy and Processes