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The failure of an A/C system often results in the introduction of contaminants to the A/C system. The sources of the contaminants include debris from damaged components and debris from the surrounding environment. Returning the A/C system to service requires the removal of these contaminants from any reused components. The recommended approach to cleaning contaminated components and systems is to flush with a solvent flushing machine. Previous internal studies have concluded that solvent flushing will remove all contaminants, restoring component and system performance. Many commercial refrigerant recovery and recharge machines include a refrigerant “flush” feature which can flush oil from the system and components with the systems refrigerant. The effectiveness of using the “flush” feature of a refrigerant recovery and recharge machine with an added in-line filter to remove contaminants is investigated.

This paper summarizes hot surface ignition characteristics of R134a and R1234yf automotive air conditioning fluids on typical under-hood automotive surfaces that possess sufficient heat to ignite flammable or combustible fluids. It further investigates the effect, if any, that these two different fluids may have on the propagation of a fire in two identically equipped vehicles under similar test conditions. This testing, in part, is in response to the United States Environmental Protection Agency's proposal which seeks comments concerning the proposed replacement of the current R134a air conditioning refrigerant with R1234yf. R134a is currently regarded as the global choice for automotive air conditioning systems however the EPA classifies it as an ozone-depleting substance (ODS) and is tasked with proposing and reviewing alternatives that do not contribute to stratospheric ozone depletion.