1.ABSTRACTRegulations on the use of chlorofluorocarbons (CFCs) are being adopted around the world to protect the ozone layer from these chemicals. It is Nissan's position that environmental protection is one of the most important issues facing automotive engineers today. Accordingly, with the aim of ensuring a healthier environment, we have been working for approximately three years on the development of an automotive air conditioning system using the HFC-134a refrigerant in place of CFC-12. Starting with the introduction of this air conditioning system in a new production model scheduled for release in March 1992, the system is expected to be used in all new models for North America by the end of 1993.This paper describes the HFC-134a automotive air conditioning system from the standpoint of the design changes required in comparison with a conventional CFC-12 system and technical measures needed for vehicle application. It also discusses the development work done on materials and reliability of air conditioner components.