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Extensive vehicle fleet testing, followed by laboratory analysis of various vital parts of the air-conditioning systems, have been performed in order to develop a procedure for retrofitting existing CFC-12 automotive air-conditioning systems to HFC-134a. Testing shows that a compressor in good condition that has previously been used with CFC-12, can be re-used with HFC-134a provided that the appropriate oil, desiccant and elastomer is used. Testing has also shown that flushing the system is not necessary. The procedure in this paper was developed as a result of testing and proposes a procedure that will maintain an “acceptable” life of the compressor at a reasonable cost.

The air conditioning systems of a fleet of sixteen (16) globally distributed vehicles have been retrofit to HFC-134a and ester-based lubricants. The variables of a generic flush-type retrofit procedure have been systematically changed. The effects of compressor condition (new or pre-conditioned), desiccant type (re-used XH-5 or new XH-7), evacuation times, and charge of mineral oil and HFC-134a were examined, in an attempt to better understand the significance of these specific variables on performance and durability of mobile air conditioning systems under retrofit conditions. Initial performance, measured qualitatively by cooling performance and quantitatively by compressor clutch cycling, is judged to be acceptable. Additional information will be provided, as available, on long-term durability of these systems.