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Impending reductions in chlorofluorocarbon production, with a complete phaseout likely by the year 2000, make it necessary to develop CFC-12 replacement refrigerants suitable for automotive air conditioning systems originally designed for CFC-12. Azeotrope-like ternary blends have been developed for this application, providing dramatic reductions in ozone depletion and global warming potentials, plus cooling performance and compressor discharge conditions essentially the same as CFC-12. Materials compatibility data are presented to aid in developing retrofit requirements.

A search for replacements for CFC-12 in automotive air conditioning has led to the discovery of near azeotropelike ternary blends of HCFC-22, HFC-152a, and CFC-114 or HCFC-124. Ozone depletion potential is reduced to 0.42 with the blend containing CFC-U4, and to 0.03 with the blend containing HCFC-124. The blends provide automotive cooling performance slightly better than CFC-12, have good oil/refrigerant/metals stability, and will not become flammable during hose permeation or vapor leaks. Based on initial tests, the blends appear to be viable CFC-12 replacements for vehicles equipped with nylon lined refrigerant hoses, alkylbenzene oil as compressor lubricant, and possibly molecular sieve desiccant of three Angstrom pore size.