In July, 1992 The Environmental Protection Agency (EPA) issued its final rule of section 604 of the Clean Air Act Amendments of 1990. The rule limits the usage, production and servicing of air-conditioning systems using CFC-12 (R-12) and HCFC-22 (R-22) refrigerants. The purpose of this action is to limit the deterioration of the stratospheric ozone layer. The reduction of the ozone allows ultraviolet radiation, type-B (UV-B), to penetrate and project down onto the earth. The act will affect the fleet operator in ways that may not have yet been explored. Specifically, operators will be faced with spending thousands of dollars on technology, as an industry and as individuals, to facilitate the necessary air-conditioning system conversions to provide compliance with the law and comfort for passengers. The need to develop an acceptable R-12 retrofit program has become a reality. This paper will outline the techniques for a successful R-12 to R-134a refrigerant conversion. The emphasis of this paper is to familiarize the fleet operator, in a single source of information format, with the use of R-134a, so that as the R-12 production ban approaches, vehicles can be converted effectively in a timely cost effective manner.