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HFC-134a is the refrigerant of choice to replace CFC-12 in automotive air conditioning. The purpose of this bulletin is to communicate the current test status of HFC-134a for use in new automotive air conditioning systems. It expands on the SAE Technical Paper (#890305)-“Performance Comparison of HFC-134a and CFC-12 in an Automotive Air Conditioning System” presented by Du Pont at the 1989 SAE International Congress and Exposition. Topics covered in this paper include: Environmental Impact Refrigerant Properties Heat Transfer Refrigeration Performance Materials Compatibility Hoses Elastomers Desiccants Metals Lubricants Solubility Lubricity Based on the test work completed, HFC-134a is not a “drop-in” replacement for CFC-12 in most existing systems. Depending on the system, certain design modifications may be required to achieve optimum performance and durability. The significant conclusions from this study are listed on page 12.

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.