R-22 REFRIGERANT INCOMPATIBILITY WITH R-12

R-22 REFRIGERANT

Vehicles Affected: ALL TRUCK MODELS -----------------

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.