Concerns about global warming and climate change, combined with the inclusion of HFCs in the Kyoto Protocol as controlled gases, obligate the automotive air conditioning industry to assess the global warming impact of its HFC-134a emissions and develop cost effective mitigation strategies. One option would be replacing HFC-134a with a refrigerant with lower overall global warming impact. This paper demonstrates the feasibility of a secondary loop A/C system in automotive applications. The value of such a system is that it excludes refrigerant from the passenger compartment, thereby allowing the use of non-inert alternate refrigerants, such as hydrocarbons. It includes actual on-vehicle comparisons of A/C cooling performance and system energy requirements for secondary loop versus the current HFC-134a system. Also included is an assessment of the global warming impact advantage offered by a secondary loop A/C system.