ACCESSORY DRIVE BELT COMES OFF NO A/C (NEW COMPRESSOR DESIGN)

SUBJECT: ACCESSORY DRIVE BELT COMES OFF OR NO AIR CONDITIONING (NEW COMPRESSOR DESIGN)

VEHICLES AFFECTED: 1993 "C/K" TRUCK (VINS H,K,Z)

CONDITION:

Some owners of early built 1993 C/K trucks with 4.3L (LB4), 5.OL (LO3), or 5.7L (LO5) engines may comment on their accessory drive belt coming off when the air conditioner (A/C) is on, or of no air conditioning.

CAUSE:

If the cause of the no air conditioning comment is determined to be a damaged electrical connector on the compressor and there is no obvious reason for the belt coming off, the cause could be "slugging" of the A/C compressor. "Slugging" is caused by liquid refrigerant passing through the compressor.

CORRECTION:

In November 1992, a change was made in the compressor to reduce the effect of "slugging." Trucks built before the VIN breakpoints listed below or having a compressor built before November 16, 1992 may need a new compressor. The new compressor part number is 12355387. Be sure the date code on the new compressor indicates manufacture after November 16, 1992 (see illustration for code location).

Plant Breakpoint Division

Fort Wayne PZ576543 GMC Truck (VIN Code Z) PZ152679 Chevrolet

Pontiac East PE521629 GMC Truck (VIN Code E) PE150167 Chevrolet

Oshawa P1524595 GMC Truck (VIN Code 1) P1163241 Chevrolet

Janesville PJ337023 (VIN Code J)

IMPORTANT: Before installing an A/C service compressor, the oil in the compressor should be drained. All service compressors are shipped with 6 oz. of oil. If the oil is not drained, the cooling capacity of the A/C system will be severely restricted. Refer to the appropriate service manual (Section 1 B) for the correct amount of oil to be added when charging the system.

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.