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Installation and modification of A/C systems for US and imported vehicles

By Ward Atkinson

Members have requested information regarding requirements that apply to vehicles produced by OEM vehicle manufacturers, commercial upfitters and independent A/C repair or service facilities that install or modify mobile A/C systems.
All A/C refrigerants listed as acceptable, including R-134a and R-1234yf, are subject to use conditions requiring labeling and the use of unique fittings. EPA is requiring the same use conditions for R-1234yf in newly manufactured medium duty passenger vehicles, HD pickup trucks and complete HD vans as it mandates in newly manufactured cars and light duty trucks.

A/C systems designed to use R-1234yf must meet the requirements of SAE J639, Safety Standards for Motor Vehicle Refrigerant Vapor Compression Systems. This document sets safety standards that include unique fittings; a warning label indicating the refrigerant’s identity and notification that it is a mildly flammable refrigerant (class A2L); and requirements for engineering design strategies that include a high-pressure compressor cutoff switch and location of pressure relief devices.

Designing the refrigerant circuit and connections to avoid refrigerant seeping into the passenger cabin ensures it is unlikely to enter the passenger cabin if there is a leak. Keeping refrigerant out of the passenger cabin minimizes the possibility there would be sufficient levels of refrigerant to reach flammable concentrations or hydrogen fluoride (HF) would be formed and transported where passengers might be exposed.

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