R4 A/C COMPRESSOR MOAN, VIBRATION NOISE

SUBJECT: R4 AIR CONDITIONING COMPRESSOR MOAN/VIBRATION/NOISE

MODEL and YEAR: 1987-89 C/K, L/M, R/V, S/T, G AND P TRUCKS WITH SERPENTINE BELTS

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 89-280-1B. THE ORANGE AND BLACK LABEL IS NO LONGER USED. ALL COPIES OF 89-280-1B SHOULD BE DISCARDED.

All R4 compressors currently available are built to the latest design specifications, therefore, at the start of production for 1992 models the special orange and black label referred to in Dealer Service Bulletin 89-280-1B is no longer used for either production or service parts.

When investigating an A/C Moan/Vibration/Noise condition on a 1987-1989 light duty truck, refer to the appropriate bulletin listed below.

CHEVROLET BULLETIN NO. MODELS ---------------------- ------ 88-413-1B 1985-88 ALL LIGHT DUTY WITHOUT SERPENTINE BELT DRIVE

89-07-1B 1987-89 M-VANS WITH 4.3L ENGINES

90-331-1B 1989-90 G2 AND G3 W/ 6.2L DIESELS

90-363-1B 1987-90 S/T TRUCKS W/ 2.8L ENGINES

91-505-1B 1988-91 C/K

92-274-1A 1987-92 S/T TRUCKS W/ 2.8L ENGINES

92-276-1B 1988-92 C/K TRUCKS

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.