:This paper reviews vehicular wind tunnel tests that were carried out on two automotive air conditioning systems. The test data compare the performance of the air conditioning systems utilizing refrigerants HFC-134a and CFC-12 with various heat exchangers. Heat exchanger selection was found to influence refrigerant charge levels. This will be important in the future when more costly HFC-134a becomes the refrigerant of choice.CFC-12 HAS LONG BEEN THE REFRIGERANT OF CHOICE for automotive air conditioning systems. Unfortunately, scientists have linked CFC-12 and other fully halogenated refrigerants to the destruction of the world's ozone layer. In addition, CFC-12 and other fully halogenated refrigerants are “greenhouse” gases, accounting for about 25% of the global warming that has taken place (1). The most promising environmentally safe refrigerant for replacement of CFC-12 appears to be HFC-134a. The automotive engineering community needs a better understanding of how HFC-134a will affect air conditioning performance if it is to adequately design future systems. This paper compares the performance of CFC-12 and HFC-134a during air conditioning tests conducted in a “vehicular” wind tunnel.