TECHNICAL INFORMATIONEXCESSIVE QUANTITY OF COMPRESSOR OIL IN REFRIGERATION SYSTEM COMPONENTS
1 - INTRODUCTION
The main objective of this technical information is to clarify
aspects related to oil circulation in refrigeration systems,with emphasis on the following: The excessive presence of compressor oil inrefrigeration system components.

 Excessive oil pumping in hermetic compressors.

In domestic refrigeration systems by mechanical vapor
compression, which use compressors whose lubricating
oil is miscible with the refrigerant (gas), oil distribution isboth acceptable and common by the components ofwhich it consists. On the other hand an excessive oilpresence in these components can be wrongly associatedwith a certain compressor defect, being on mostoccasions the result of incorrect diagnoses.

For a system to be rejected, it is necessary that theestablished parameter temperature is not reached within
the determined time. Normally this system makes thecompressor “suspect”, as it is responsible for the productrefrigeration and a premature judgment can result in it
being condemned for “low capacity”.
The system is then opened and the compressor isremoved. During this operation it is common to notice thepresence of a certain quantity of oil in the piping,
generated from the evaporator and condenser. At thistime, the association of lack of capacity and excessive oilcirculation can also unduly condemn the compressor once
there are other factors that equally contribute to the lack ofrefrigeration capacity, as well as by the presence of oil inthe components.

3 - IDENTIFYING INFLUENCING CAUSES
2 - IDENTIFYING THE DEFECT
Regardless of the type and degree of the modernization of
the end of assembly line tests applied to refrigeration
systems, the system’s internal temperature, together withthe cooling time of the same, are still the criteria most used
for approval in system performance tests. Thermocouples
or thermometers are placed inside the cabinet and/or
freezer compartment. After a certain system functioning
period, the temperature is then checked. Depending on
the result, the system will be approved or rejectedaccording to the following flowchart:

The most influencing factors that can cause a system topresent “low capacity” or “oil presence in its components”
are:
INCORRECT REFRIGERANT (GAS) LOADING PROCESS inadequate equipment defective equipment
 incorrect procedure

INADEQUATE REFRIGERANT (GAS) LOAD
 leakage in system - welding problems
 leakage from components

BADLY PROJECTED SYSTEM
 inadequate evaporator circuit piping diameter deviation to cold plate number of parallel pipes
 internal volume

OTHER CAUSES
 energy cut during end of assembly line test
 thermostat with problem
 partial piping obstruction
 problem with compressor starting system leakage of refrigerant gas from capillary tube
 defective compressor
 incorrect diagnosis

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TECHNICAL INFORMATIONEXCESSIVE QUANTITY OF COMPRESSOR OIL IN REFRIGERATION SYSTEM COMPONENTS
4 - IDENTIFICATION OF POSSIBLE CAUSES X
PROCEDURES
INCORRECT REFRIGERANT (GAS)LOADING PROCESS
Procedures:
 Check that the equipment used is compatible with theTHERMOSTAT WITH PROBLEM
Procedures:
 Check that the thermostat is operating within the on andoff range according to the manufacturer’s technicalspecification. There are cases where the thermostat isunbalanced, thus causing a compressor disconnection
before the internal system temperature reaches thespecified value.

process to be carried out.

 Check any abnormal equipment functioning. Consult themanufacturer’s Instruction Manual.

 Check that the specific procedures are being correctlyfollowed.

INADEQUATE REFRIGERANT (GAS) LOAD
Procedures: Periodically check that the refrigerant (gas) loading

equipment is injecting the specific quantity of refrigerant
for each type of refrigeration system.

 Check for the existence of any type of leakage due towelding failure or defective components with specificequipment.

POORLY DESIGNED SYSTEM
Procedures:

PARTIAL TUBING OBSTRUCTIONProcedures:
 Check that all welded joints were carried out in such away so as not to permit any type of obstructions whether
due to excessive welding material or folding or crushingof the tube. Special care must be taken in the cutting of
the capillary tube to avoid burrs and crushing. Humidity
in the system can cause blockage due to freezing at
some point inside the capillary tube when T  0oC. Thiscan be easily detected by switching the system off andthen switching it on again after a certain time. If thesystem returns to normal functioning and shortly
afterwards the problems repeats itself (loss of capacity)
this is strong evidence of humidity freezing inside thecapillary. In this case, check that the vacuum process
is adequate and substitute the filter drier. Partial or total
obstructions tend to increase system functioningpressures and temperatures, reducing its working life aswell as its efficiency, without considering the possibilityof total capacity loss in the case of compressor gasket
rupture due to excessive pressure.

 Tests carried out by Embraco did not prove that

irregularities in refrigeration system projects were related
to this defect. However, we requested that special
attention be paid to the evaporator circuit, particularly
concerning piping diameters, number of parallel pipes,
internal volumes, and deviations to the cold plate, when
this was planned in the project.

OTHER CAUSESCOMPRESSOR STARTING SYSTEM WITH PROBLEM
Procedures:
 Check that the compressor electrical components (relayand thermal protector) are those specified by themanufacturer or if there are any irregularities of thesame. If this is affirmative, substitute the defective
components.

POWER OUTAGE DURING ASSEMBLY LINE FINAL TESTLEAKAGE OF REFRIGERANT (GAS) FROM THE
CAPILLARY TUBE

Procedures:

Procedures:

 Check whether there is an energy cut during the Check that there is no refrigerant leakage at the joining

carrying out of the final test of assembly line. Should thisprove affirmative, repeat the test.

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of the capillary tube X suction line which can possibly
occur in roll-bond evaporators with coaxial inlet/outlet.

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TECHNICAL INFORMATIONEXCESSIVE QUANTITY OF COMPRESSOR OIL IN REFRIGERATION SYSTEM COMPONENTS
DEFECTIVE COMPRESSOR
Procedures: If after having carried out the previously mentioned

verifications a suspected defect persists, thecompressor could have some problem. If this happens,
contact Embraco who will provide complete instructions
for the internal testing of this compressor at theirlaboratories.

actually contribute to the oil accumulation in systemcomponents. The following graph shows the quantity ofoil retained in a system in relation to the refrigerant (gas)load present in same.
 The graphic below shows that the smaller the refrigerantload present inside a refrigeration system, the greater
the quantity of retained oil in components of same.
Therefore, the quantity of oil found in systemcomponents with an incorrect refrigerant load or
reduced by any type of leakage, will be greater.

INCORRECT DIAGNOSIS
Procedures: The correct identification of any defect whatsoever andits causes is a predominant factor for solution of thesame. Therefore, verify, step by step, all of the previous
listed items before reaching a final diagnosis.

5 - GENERAL COMMENTS
 Any suspicion of a refrigeration system presenting an oil

excess in components can only be proven with theremoval of the compressor from the system. This
problem cannot be solely diagnosed by associating itwith “capacity loss” defect.

 The presence of oil in the system components does notaffect performance of same. Systems whose
components were inundated with oil did not present any
capacity loss whatsoever nor an increase of evaporation
temperature.

 Compressors tested outside the refrigeration systemwith suction and discharge open to the atmosphere canpresent spray or even small drops of oil through thedischarge connector. There is no association with reality,i.e., with the compressor mounted in the system,
because even together with the refrigerant (gas) the oil
reduces its viscosity, thus increasing its free circulation
through the refrigeration circuit.

 In tests carried out by Embraco on compressors with ahigh rate of oil circulation there were no irregularities in
the functioning conditions of the systems in which theywere mounted. Of the influencing causes stated initem 3, only those related to the refrigerant (gas) load

 All previously listed causes can be directly or indirectly

be related to the compressor low capacity symptom.
Tests carried out by Embraco on compressors with ahigher than normal oil circulation rate, did not reveal any
impairment with the performance of the tested systems.
Thus being, we suggest that all causes be investigated,
step by step, emphasizing mainly those related to therefrigerant (gas) load.

Note: After replacement, the compressor and it’s accessories must have proper processing, and the components must be recycledaccording to the material group (ferrous, non-ferrous, polymers, oils, ...) directives. These recomendations are intended to minimize theadverse impacts that may be caused to the environment.

Embraco is participating in the United Nations Global Compact.

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