This paper profiles the North American retrofit fleets (vehicle types and run conditions), and describes the results seen with these trials. After two cooling seasons in both Australia and North America, we have begun to remove vehicles from the fleet, and examine them for durability and system chemistries.To date, there have been no systematic performance or durability issues. The service requirements of the fleet have been typical of those seen with equivalent CFC-12 vehicles, as shown by specific examples.Results indicate that OEM rubber hoses likely provide sufficient containment for HFC-134a in retrofit situations, and that adequate compressor durability may be expected with the lubricants used. Bench testing with molecular sieve and silica type desiccants at least suggest that existing desiccants may be sufficiently stable to be used in retrofit conditions. This is indirectly supported by fleet tests, though at this point, there is still insufficient field information to make conclusive recommendations in this area.