Automotive AC – Retrofitting R12 Systems to R134a

Vehicles that were built with AC systems that used R12 as the refrigerant were used from the beginning days of mobile AC units on cars and trucks up until 1992. R12 was a very reliable refrigerant that did a great job of cooling the cab of vehicles. When it became evident that the release of chlorofluorocarbon (CFC) into the atmosphere was causing deterioration of the atmospheric layer called the ozone, a new refrigerant was introduced to mobile AC systems. Beginning in 1993, all cars and trucks sold in the United States contained R134a. Slowly, the supply of R12 was reduced, which caused the cost of this substance to rise quickly. This circumstance caused the need to change these older systems over to the R134a. This section of the chapter will provide details on how to perform a retrofit correctly on these older vehicles.

Pre-1993 Vehicles

Vehicles that are in the age range of 1992 back to about 1975 that are still in service are not very plentiful, but there are still a few thousand of them on the road. When a vehicle in this age range is still being driven and the AC system is needed or desired, then a decision must be made on how to proceed with repairing it. First of all, if a vehicle in this age range still has a functioning AC system, then consider yourself very fortunate. No repairs need to be made except for items such as belts and cleaning the condenser coils. Most vehicles in this era with AC will have an inoperative system that must be diagnosed and repaired. Normal diagnosis procedures such as the ones discussed in chapter 4 can be used to troubleshoot problems in the AC system.

After determining what is at fault in the AC system, it must be decided whether or not to perform a retrofit of the system while repairing the other faults. Nearly always, the correct decision is to perform a retrofit of the system during the repair process. The steps below cover the retrofit process.

This retrofit kit comes with three cans of R134a refrigerant, oil, a charge hose, service fittings, and the decal. The box states that this process can be completed in 10 minutes, but to do it right it will take a couple of

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