Refrigerator Oil; Refrigerator Oil With Hfc Based Refrigerants; Influence Of Contaminants - Mitsubishi Electric CITY MULTI PQRY-P200YMF-B Service Handbook

A A A A A REFRIGERATOR OIL

[1] Refrigerator Oil with HFC Based Refrigerants

A different refrigerator oil is used with the new refrigerant than with R22.
Note:
Since the type of refrigerator oil used with R22 is different from that used with R407C, the different types of
refrigerant oil should not be mixed and used together.

[2] Influence of Contaminants

With the refrigerator oil used with the new refrigerant, it is necessary to exercise greater caution concerning the
mixing of contaminants than with the mineral oil used with the previous refrigerant. Therefore, it is necessary to get
a sufficient grasp of the basic items in the following table to understand the harm that is caused to the refrigeration
cycle from deficiencies involving the oil charging process, and to prevent contaminants from being mixed in.
Influence of oil with contaminants mixed in on the refrigeration cycle
Cause
Mixing with moisture
Mixing with air
Mixing of Dirt,
foreign contami-
matter nants
Mineral oil,
etc.
Contaminants is a general term for moisture, air, process oil, dirt, other refrigerants and other refrigerator oils, etc.
Symptom
Freezing of expansion
valves and capillaries
Hydrolysis Sludge formation
Generation of acids
Oxidation
Oxidation Aging of oil
Adhesion to the expansion valves and to cap-
illaries
Mixing of foreign matter in the compressor
Sludge formation, adhesion
Aging of oil
Influence on the refrigeration cycle
Clogging of expansion
valves and capillaries
Compressor overheating
Poor motor insulation
Copper plating on sliding
parts
Sticking of sliding parts
Expansion valve, capillaries
Clogging of the drier
Sticking of sliding parts
Clogging of expansion
valve, capillaries
Sticking of sliding parts
–147–
Cooling deficiencies
Burnout of the motor
Locking
Cooling deficiencies
Overheating of the
compressor
Cooling deficiencies
Overheating of the
compressor