This SAE Standard Practice is restricted to refrigerant vapor compression systems that provide cooling and/or heating for the passenger compartment. This document provides design standards for refrigerant containment and safety for these systems. Also included are cautionary statements for the mobile air conditioning service industry to alert service technicians to the inadvisability and the possible health and safety effects associated with venting refrigerant during service. It is not intended to restrict the use, or further development, of other types of refrigeration systems for passenger compartment cooling. Should other systems be found practical, this document may be amended or an additional standard safety practice created for such systems. This document addresses only CFC-12 (R-12), HFC-134a (R-134a), HFC152a (R-152a) a flammable gas and carbon dioxide (R-744) refrigerants. To prevent system contamination all refrigerants used in mobile air conditioning vapor compression systems require unique service fittings. The unique service fittings minimize the potential for system refrigerant contamination during service activity.