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This paper and presentation compare the thermal, economic and climate performance of existing direct expansion motor vehicle air conditioners (DX-MACs) using hydrofluorocarbon (HFC)-134a (global warming potential (GWP) =1300) with secondary-loop MACs (SL-MACs) using hydrofluoroolefin (HFO)-1234yf (GWP < 1) and HFC-152a (GWP = 138), both of which satisfy the European Union (EU) and Japan F-gas regulations and are listed as acceptable by the US Environmental Protection Agency (US EPA). In addition to a technical review of the SL-MAC system, the paper includes a part-by-part system manufacturing cost comparison and itemized ownership cost comparison taking into account fuel savings and reduced maintenance. The paper is timely because the Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer now requires both developed and developing countries to phase down the production and consumption of HFCs and at the same time encourages increases in energy efficiency.