Conversion From R12 To R134a, "Retrofit"

WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Conversion From R12 To R134a

Courtesy of VOLVO CARS OF NORTH AMERICA.

Conversion kit contents

The contents of the kit vary depending on the car and model year, but in all cases ester oil, a receiver drier and an expansion pipe or a TEV valve is included.

For certain cars, in addition to the basic kit there are also one or more supplementary kits (pipes, shaft seal for the compressor).

The cooling performance is unchanged by the conversion.

Why replace the oil and components?

Mineral oil which is used for R12 does not mix with R134a. Most of the mineral oil must therefore be replaced with ester oil. Ester oil can be mixed with both R134a and the remaining mineral oil in the system. In addition it has little effect on the material in the O-ring. As a result, only the O-rings on the connections that are opened in order to replace a component require replacing.

NOTE: On Sanden 508-510 and 709 compressors the shaft seal must be replaced with a seal adapted for R134a. This also applies when a replacement compressor is being used in a converted system.

The receiver drier must be replaced because:

the drying agent intended for R12 becomes chemically unstable and brakes down if it is exposed to R134a.
sufficient service life can be obtained (the old drying agent by may have consumed a quantity of water).

Expansion pipe/TEV valve must be replaced to obtain the correct flow of refrigerant (the molecules in R12 are larger than in R134a).