R4 A/C COMPRESSOR MOAN, VIBRATION NOISE

SUBJECT: R4 A/C COMPRESSOR MOAN/VIBRATION/NOISE BULLETIN CANCELLATION

MODELS: 1987-89 LIGHT DUTY TRUCKS WITH SERPENTINE BELTS

THIS BULLETIN CANCELS AND REPLACES GMC TRUCK SERVICE BULLETIN 89-1B-118 DATED DECEMBER 1989 AND HAS BEEN REVISED TO CANCEL SERVICE INFORMATION WHICH IS NO LONGER APPLICABLE. ALL COPIES OF 89-1B-118 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 GMC Truck Bulletin # 89-1B-118 (Corporate # 961205R) 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.

GMC Number Corporate Models ---------- Number ------ --------- 88-T-209 861203R 1985-88 ALL LIGHT DUTY WITHOUT SERPENTINE BELT DRIVE 89-T-02 831212R 1987-89 M-VANS WITH 4.3L ENGINES 90-1B-97 031204R 1989-90 G2 AND G3 W/ 6.2L DIESELS 90-1B-103 061205R 1987-90 S/T TRUCKS W/ 2.8L ENGINES 91-1B-188 061201R 1988-91 C/K 92-1B-121 821202R 1987-92 S/T TRUCKS W/ 2.8L ENGINES 92-1B-123 261203 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.