Technical Support Document for Acceptability 

Listing of HFO-1234yf for Motor Vehicle Air 

Conditioning in Limited Heavy-Duty Applications

P REPARED FOR :

 Stratospheric Protection Division 

Office of Air and Radiation 

U.S. Environmental Protection Agency 

Washington, D.C. 20460 

P REPARED BY :

ICF International 

1725 Eye Street, NW 

Washington, DC 20006 

M ARCH 21, 201 6
1

1. Introduction 

Motor vehicle air conditioner (MVAC) systems cool the passenger compartment of passenger cars, lightduty (LD) trucks, heavy-duty vehicles (HDV), off-road vehicles, buses, and passenger rail vehicles. The 

MVAC sector historically relied on CFC-12, and to a more limited extent, HCFC-22 in passenger rail and 

buses, both of which are ozone depleting substances (ODS). In advance of the 1996 phaseout of CFC-12 

and the continued phaseout of HCFCs, the U.S. MVAC industry largely transitioned away from ODS by 

1994, relying most heavily on a high-GWP refrigerant, HFC-134a. Today, HFC-134a remains the 

predominant refrigerant; however, low-GWP alternatives are entering the U.S. market for light-duty 

vehicles (LDVs), facilitated by approval of alternatives, including hydrofluoroolefin (HFO)-1234yf, by 

EPA’s SNAP program and the availability of air conditioning credits to meet greenhouse gas (GHG)

standards for LDVs.

In 2011, EPA’s SNAP program found HFO-1234yf acceptable, subject to use conditions, in MVAC systems

for new passenger cars and LD trucks. EPA is now evaluating the use of HFO-1234yf in MVAC systems of 

limited types of HDVs, specifically medium-duty passenger vehicles (MDPV), heavy-duty (HD) pickup 

trucks, and complete HD vans.

The purpose of this technical support document is to provide the following:

• Summarize background information on MDPVs and HD pickup trucks and vans in terms of 

vehicle types, market size, and MVAC characteristics in the United States;

• Analyze the ratio of MVAC refrigerant charge size to passenger compartment volume for 

these vehicles as compared to LDVs; and 

• Conduct a qualitative analysis of risks anticipated for these vehicle types as compared to 

risks assessed for the use of HFO-1234yf in LDVs. 

2. Background Information 

This section provides background information on the current U.S. market for MDPVs, HD pickup trucks,

and HD vans, specifically the following:

• Vehicle Types

• Fleet Estimates

• MVAC Characteristics

2.1 Vehicle Types

Vehicles are typically classified by their gross vehicle weight rating (GVWR), which is the maximum 

loaded operating weight of the vehicle including cargo and passengers. HDVs include all on-road vehicles 

rated at or above 8,500 pounds GVWR which meet the criteria outlined in 40 CFR 86.1803-01. HDVs with 

GVWR between 8,501 – 10,000 pounds and 10,001 – 14,000 pounds are classified as Class 2b and Class 3 

vehicles, respectively. This analysis includes Class 2b and 3 MDPVs,1 HD passenger vans, HD cargo vans, 

and HD pickup trucks, but does not consider any vocational vehicles that may also be in included in the 

GVWR range (e.g., chassis cabs, utility “bucket” trucks, refuse trucks, ambulances, tow trucks, and dump 

trucks). For the purposes of this analysis, EPA is not considering vehicle types with a GVWR above 

14,000 pounds.

 1 MDPVs include passenger vans with GVWR between 8,501 pounds and 14,000 pounds. While MDPVs are 

classified as HD vehicles by GVWR, their fuel economy and GHG emissions are regulated with LDVs. 
2

Figure 1. Examples of Class 2b and 3 Van and Pickup Truck

Source: EPA (2011b)

HDVs are commonly used as work vehicles. HD pickup trucks are typically the HD versions of their

higher-volume LD counterparts (ICCT 2015). For example, the Silverado 1500, Ram 1500, and Ford F-150 

are the LD counterparts of the HD Silverado 2500/3500, Ram 2500/3500, and Ford F-250/F-350/F-450

pickup trucks. Approximately 90 percent of HD pickups and HD vans are 3⁄4-ton and 1-ton pickup trucks, 

15-passenger vans, and large work vans that are sold by vehicle manufacturers as complete vehicles 

(EPA and NHTSA 2011a).

In the United States, MDPVs, HD pickup trucks, and HD vans are manufactured by Ford, General Motors

(GM), Fiat Chrysler Automobiles (FCA), Nissan, and Daimler. The following table provides the 

descriptions, classifications, and models of MDPVs, HD pickup trucks and HD vans.

Table 1. Descriptions and Classifications of MDPVs, HD Pickup Trucks, and HD Vans

Vehicle Class

Gross Vehicle 

Weight Rating 

(GVWR) (lbs)

Vehicle Types Vehicle Models

Class 2b 8,501 – 10,000 Van, Passenger Chevrolet Express Passenger

GMC Savana Passenger

Ford E-Series Econoline

Nissan NV Passenger

Van, Cargo Chevrolet Express Cargo

Daimler Sprinter

GMC Savana Cargo

Nissan NV 2500 HD Cargo

Nissan NV 3500 HD Cargo

Ram Promaster

Pickup Truck Chevrolet Silverado 2500

Dodge Ram 2500

GMC Sierra 2500 Denali

GMC Sierra 2500 HD

Class 3 10,001 – 14,000 Van, Passenger Ford Transit Wagon XL/XLT

Van, Cargo Ford Transit Van

Pickup Truck Chevrolet Silverado 3500

Ford F-250

Ford F-350

Ford F-450

GMC Sierra 3500 HD

Ram 2500 SLT

Ram 3500 SLT

Ram 3500 Tradesman
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As presented in Table 1, in the Class 2b and Class 3 vehicle markets, Ford produces the F-250, F-350, and 

F-450 “Super-Duty” pickup trucks, GM produces the Silverado, Sierra HD series HD pickup trucks, and 

FCA produces the Ram HD pickup truck series. Class 2b and Class 3 HD vans are categorized as either 

passenger or cargo vans, with vehicle model series often serving both functions depending on the 

inclusion of additional rows of passenger seats in the extended sections of the vehicle (e.g., Nissan NV 

series). The HD van market includes the Transit (Ford) which replaced the E-Series Econoline (Ford),

Savana and Express series (GM), Promaster (FCA), NV series (Nissan), and Sprinter (Daimler). Table 2, 

below, presents the estimated market share for HD pickup trucks and vans (EPA 2015). 

Table 2. Market Share for HD Pickup Trucks and HD Vansa

Manufacturer Style

2015 Model 

Year (MY)

Market Share

Daimler

Van

3%

Fiat 2%

Ford 16%

General Motors 12%

Nissan 2%

Daimler

Pickup

<1%

Fiat 14%

Ford 28%

General Motors 23%

Nissan <1% a Equivalent information on MDPVs is not included 

because it was not readily available.

2.2 Vehicle Market

Available information on vehicle market estimates (i.e., vehicle sales or new registrations) for the HDV

types included in this analysis within the United States are presented in this section. According to ICCT 

(2015), Class 2b and Class 3 HD pickup trucks and HD vans represent more than 50 percent of all HDV

sales in the United States.

The figure below was developed by ICCT (2015) using three data sources [i.e., Wards (2012), Automotive 

News (2014), and BEA (2014)] on total new vehicle registrations by calendar year of vehicles less than 

14,001 pounds GVWR. By subtracting the number of registrations of LDVs (i.e., vehicles less than 8,501

pounds) by model year (MY) available from EPA from the data on total sales of vehicles less than 14,001 

pounds, there were approximately 450,000 newly registered Class 2b and Class 3 vehicles in 2010, 1.0 

million in 2012, and 1.2 million in 2013 (ICCT 2015).
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Figure 2. Total new Class 1 – 3 vehicles (i.e., under 14,001 GVWR) and total LDVs

Source: ICCT (2015)

The following table summarizes readily available data on Class 2b and Class 3 vehicle sales or new 

registrations from 2009 – 2015. The average total annual sales of Class 2b and 3 vehicles between 2009 

and 2015 was approximately 740,000 vehicles, with estimates ranging from a high of 1.2 million in 2013 

to a low of 450,000 in 2010. Discrepancies between data sources are likely due to overlap of vehicle 

categories across various sources. For example, some estimates only include HD pickup trucks and vans 

while other sources include all Class 2b and Class 3 vehicles.

Table 3. Vehicle Registrations or Sales of Class 2b and Class 3 Vehicles from 2009 – 2015

Year Class 2b 

Sales

Class 3 

Sales Total Sales Source

2009 - 111,704b - US DOE 2011

2010

590,000 200,000 790,000 US EPA and NHTSA 2015

- - 450,000 ICCT 2015

- 160,000 - ORNL 2015

- - 580,000 ICCT 2015

2011 - 190,000 - ORNL 2015

2012

- - 1,000,000 ICCT 2015

340,000 170,000 510,000 Polk 2013

- 220,000 - ORNL 2015

2013 - - 1,200,000 ICCT 2015

- 250,000 - ORNL 2015

2014 506,989 131,120 638,109 EPA & NHTSA 2015

2015 500,000 150,000 650,000 EPA & NHTSA 2015
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2.3 MVAC Characteristics

HD pickup trucks and HD vans share many design similarities with their lighter counterparts, including 

their vehicle design, work attributes, and technology availability (ICCT 2015). The MVAC systems in these 

vehicles as well as MDPVs are very similar to those used in LD applications. Differences may exist in 

terms of cooling capacity (e.g., based on cabin volume), system layout (e.g., the number of evaporators), 

and the durability requirements due to longer truck life (EPA & NHTSA 2011b).

MVAC systems in HD pickups and HD vans generally have a similar configuration and use similar 

components as their lighter counterparts. The refrigerant capacity (i.e., charge size) of MVAC systems in 

both LD and HD vehicles vary by vehicle type and cabin size. A range of reported estimates of charge 

sizes of MVAC systems using R-134a in MDPVs, HD pickups and HD vans in comparison to LD vehicles are 

summarized below.

Table 4. HFC-134a Refrigerant Charge Sizes for LD Vehicles, MDPVs, HD Pickups, and HD Vans

End-Use Charge Size (grams)

LD Vehicles 390 – 1,220

HD Van, (Passenger and Cargo) 800 – 1,600

HD Pickup Truck 600 – 765

Sources: Autozone (2015), ABI (2014), Ford (2007), Ford (2014), Ford (2015b), 

TechChoice Parts (2012), ICF (2008)

Some HD vans and other types of HDVs that are not included in this analysis have auxiliary AC systems, 

which are separate from the main AC system that is traditionally mechanically gear- or belt-driven by 

the base engine of the vehicle (EPA & NSTSA 2011). These auxiliary systems are often installed in 

addition to the main AC system (e.g., in the rear passenger or cargo area) and are not considered in this 

analysis. 

3. Refrigerant charge to passenger compartment volume ratios 

This section presents information on the highest refrigerant charge to passenger compartment volume 

ratios for the HD vehicle types addressed in this document and for LDVs addressed in ICF (2009). This 

analysis considered 38 models of vehicles from 5 manufacturers (i.e., Ford, FCA, GM, Nissan, and 

Daimler) in addition to the vehicles considered in 2009.

Refrigerant charge size data were obtained from various sources including publically available sources 

developed by manufacturers, refrigerant capacity catalogs, and automotive store websites. The range of 

charge sizes for each vehicle type is presented above in Table 4. 

Passenger compartment volume data were largely obtained from the specifications listed on the 

respective manufacturer websites. In some cases where total compartment volumes were not exactly 

provided, they were estimated using the interior dimensions and the methods outlined in 40 CFR 600, 

Subpart D.2

The following table presents the highest ratios identified for a variety of vehicle types, with the ratios 

highlighted in green to indicate those for the HDVs being considered in this document.. The highest ratio 

for all HD vehicle types included in this analysis is 410 g/m3 in HD pickup trucks (shown in bold font in 

Table 5), which is less than the maximum ratio identified in the analysis for HFO-1234yf in LDVs in two 

seaters (i.e., 641 g/m3

) (also shown in bold).

 2 Passenger compartment volume can be calculated as the sum of [(Head Room x Shoulder Room x Leg Room)/1728] for all 

rows of seating.
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Table 5. Vehicles with the Highest Ratio of Refrigerant Charge to Passenger Compartment 

Volume in each Vehicle Type

Vehicle Type

Passenger 

Compartment 

Size (m3)a

MAC 

Charge 

Size HFC134a 

(grams)b

Ratio of HFC134a Charge to 

Compartment 

Volume (g/m3)

Manufacturer Modelc

HD Pickup 1.87 765c 410 Ford F450 (Regular) (MY 2014)

HD Van, Cargo 9.51 1,600 168 Chevrolet Express Cargo 

HD Van, Passenger 6.50 1,600 246 Chevrolet Express Passenger

Two seaters 1.42 907 641 Mercedes-Benz Sl65 AMG (MY 2007)

Small pickup trucks 1.48 940 633 Ford Ranger

S.U.V. 3.01 1250 415 Mercury Mountaineer (W/ Aux Heat)

Standard pickup trucks 1.59 632 398 Toyota Toyota Tacoma Prerunner

Compact cars 2.63 936 355 Mercedes-Benz CLS Class (MY 2007)

Subcompact cars 2.29 794 346 BMW 650i And M6 (MY 2007)

Minicompact cars 2.10 725 346 Jaguar Jaguar XKR

Midsize cars 2.72 936 343 Mercedes-Benz E Class (MY 2007)

Large cars 2.94 794 270 BMW 750i (MY 2007)

Small station wagons 2.66 670 252 Pontiac Vibe

Minivan 4.42 1,100 249 Dodge Grand Caravan SXT Wagon

Midsize station wagonsd 3.06 475 155 Kia Rondo a Sources: ICF (2008) and vehicle manufacturer websites. Otherwise, value was estimated using methods at 40 CFR 600, Subpart D. b Sources: Motor Information Systems database unless otherwise noted. c Autozone (2015) c All models are MY 2008 unless otherwise noted. d Data were available for only 1 midsize station wagon. By default it has the ‘highest’ ratio.

4. Qualitative Risk Analysis 

HFO-1234yf is flammable when its concentration in air is in the range of 6.2 percent to 12.3 percent by 

volume (62,000 ppm to 123,000 ppm). In the presence of an ignition source (e.g., spark, open flame), a 

fire could occur when the concentration of HFO-1234yf is within these flammability limits. To determine 

whether the flammability or end-use exposure of HFO-1234yf would be a concern for LDV passengers, a 

reasonable worst-case scenario analysis was performed in 2009 to model the catastrophic release of the 

refrigerant into a vehicle (ICF 2009). Two key inputs to the model were passenger compartment volume 

(i.e., the space into which the refrigerant would leak) and the refrigerant charge size. Because passenger 

compartment volumes and refrigerant charge sizes can vary widely from model to model, ICF used the 

highest ratio of charge size to compartment volume identified (see section above) as the input into the 

model. The highest refrigerant charge to passenger compartment ratio for LDVs was determined as

approximately 641 g/m3

.

This section presents a qualitative analysis of risks anticipated for the use of HFO-1234yf in the limited 

HDV types discussed in this document as compared to the LDV types considered in the existing analysis 

conducted on the use of HFO-1234yf in LDVs (ICF 2009; Gradient 2008). To assess the potential risks 

associated with the use of HFO-1234yf in LDVs, ICF International (ICF 2009) and an SAE International 

Cooperative Research Program (CRP) (Gradient 2008) conducted risk assessments, using worst-case 

scenario box modeling and Computational Fluid Dynamics (CFD) modeling, respectively. The 

assessments evaluated the end-use exposure and flammability risks of using HFO-1234yf in LDVs by 

comparing concentrations of HFO-1234yf in the passenger compartment with the lower flammability 

limit (LFL) of 62,000 ppm following a leak from the MVAC system. 
7

The SAE CRP (Gradient 2008) conducted CFD modeling using a Ford Crown Victoria, the same vehicle 

model used by EPA to evaluate the use of R-152a and CO2 (R-744) in LDV MVAC systems (Blackwell et al. 

2006), which has a charge to compartment volume ratio of 223 g/m3

.

3 The SAE CRP concluded that there 

was a very low flammability risk due to the extremely low probability of achieving a concentration of 

HFO-1234yf above the LFL at the same time as having a sufficiently high energy source and the presence 

of oxygen to result in refrigerant ignition (Gradient 2008). 

In ICF (2009), the worst-case scenario evaluated was the Mercedes SL65 AMG two-seater, which was 

selected because it was identified as having the greatest refrigerant charge per passenger compartment 

volume ratio of all LDVs evaluated (i.e., 641 g/m3

).4 To prevent against the risk of fire or explosion, ICF 

(2009) recommended in support of EPA’s proposed rule to list HFO-1234yf for use in LDVs that all HFO1234yf MVAC systems, particularly in vehicles with high refrigerant charge to compartment volume 

ratios, should be designed to avoid occupant exposure to concentrations of HFO-1234yf above 62,000 

ppm in the passenger compartment for more than 15 seconds. EPA did not finalize this recommendation 

as a use condition for LDVs because it was determined that another use condition, which requires

manufacturers to meet all of the safety requirements in the standard SAE J639, “Safety Standards for 

Motor Vehicle Refrigerant Vapor Compression Systems,” sufficiently mitigates the risk of fire or 

explosion (March 29, 2011; 76 FR 17488). ICF (2009) also concluded that acute exposure to elevated 

concentrations of HFO-1234yf is not expected to be a toxicological concern in humans who are exposed 

following a worst-case, accidental release of the total MVAC refrigerant charge.

The results of the analysis in Section 3 of this document indicate that the highest ratio for all MDPVs, HD

pickup trucks and HD vans is 410 g/m3 in the Ford F-450, which is 231 g/m3 less than the maximum ratio 

used in the worst-case scenario in ICF (2009) (i.e., 641 g/m3

). As a result, the toxicity and flammability 

risks from using HFO-1234yf in MDPVs, HD pickup trucks, and complete HD vans will be lower than 

those from HFO-1234yf used in LDVs because of the much higher refrigerant charge to passenger 

compartment volume ratios. The analysis conducted on LDVs is sufficiently conservative to account for 

toxicity and flammability risks that could occur from the use of HFO-1234yf in MDPVs, HD pickup trucks, 

and complete HD vans.

Based on the discussion presented here, and the previous analysis, ICF believes that the risk of adverse 

health effects and fire are minimal if HFO-1234yf MVAC systems are manufactured and used in 

accordance with use conditions, and installed in MDPVs, HD pickup trucks, and complete HD vans in 

accordance with industry standards and recommendations. 

ICF concludes that the most conservative scenarios modeled by ICF (2009) for HFO-1234yf in LDVs is 

sufficiently conservative to account for potential risks of HFO-1234yf in MDPVs, HD pickup trucks, and 

complete HD vans. Therefore, the use of HFO-1234yf in the limited HDV types analyzed in this document 

indicate that potential exposure from a refrigerant leak into the passenger compartment is not expected 

to present an unreasonable risk to drivers, passengers or first responders in the case of an accident or 

collision.

 3 The charge size and passenger compartment volume of the Ford Crown Victoria used in the CFD modeling were 691 grams 

and 3.1 m3, respectively (Gradient 2008). 4 The charge size and passenger compartment volume of the Mercedes SL65 AMG two-seater used in the worst-case scenario 

box modeling were 907 grams and 1.4 m3, respectively (ICF 2009).
8

5. References 

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at: http://www.austinbaker.net/downloads/2014/2014%20ABI%20Oil%20Catalog.pdf.

Autozone, Inc. 2015. Specifications. Available online at: 

http://www.autozone.com/repairinfo/specifications/specificationsMain.jsp.

Blackwell, N., L. Bendixen, and E. Birgfeld. 2006. Risk Analysis for Alternative Refrigerant in Motor 

Vehicle Air Conditioning. September 2006. Available online at: 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OAR-2004-0488-0038.

Chevrolet. 2015. Models: 2016 Express Cargo Van, 2015 Express Passenger Van, 2015 Silverado 1500, 

2015 Silverado 2500HD, and 2015 Silverado 3500HD. Available online at: http://www.chevrolet.com.

Ford Motor Company. 2015a. Model Specifications: 2016 Chassis Cab, 2016 E-Series Cutaway, 2016 

Super Duty, 2016 Transit. Available online at: http://www.ford.com.

Ford Motor Company. 2015b. 2015 Transit Owner’s Manual. Available online at: 

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ICF International. 2008. Air Conditioning Refrigerant Charge Size to Passenger Compartment Volume 

Ratio Analysis. Confidential Memorandum Prepared for the U.S. Environmental Protection Agency. 
9

ICF International. 2009. Risk Screen on Substitutes for CFC-12 in Motor Vehicle Air Conditioning: 

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the Motor Vehicle Air Conditioning Sector under the Significant New Alternatives Policy (SNAP) Program; 

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(NHTSA). 2011a. Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for

Medium- and Heavy-Duty Engines and Vehicles; Final Rule. 76 FR 57106. Available online at: 

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