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This paper is a continuation of a series of papers presented by ICI on the North American retrofit fleet with HFC-134a. Building on our last paper, which profiled this fleet, this paper describes the results of the studies in which a number of vehicles have been removed from test, and their air-conditioning systems examined. After an update on performance and service requirements, the paper provides results which include the conditions of the compressors and other components, the quality of the refrigerant and lubricant, and the amount of the refrigerant charge retained. This information will be correlated with previous information to determine the actual efficiency of previously employed clean-out methods. The data indicates existing OEM hoses and elastomers are likely to provide sufficient containment of HFC-134a in retrofit situations. Vehicles retrofit under a variety of procedures (flushed or not) have shown good A/C performance and compressor durability.

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.