Use of R-22 refrigerant in any GMC truck A/C system is not recommended. R-22 refrigerant will not mix with the compressor lubricant currently used. Any mixture of R-12 and R-22 may cause the following to occur:
- A/C compressor relief valve to blow at idle due to the build up of head pressures. - Loss of A/C system charge due to R-22 seeping through A/C hoses. - Compressor failure due to insufficient lubrication.
R-12 is the only refrigerant that should be used in GMC truck A/C systems.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.