A/C - Noise/Vibration When Engaged

91chevy27

GMC NUMBER: 91-1B-154

GROUP: 1B Air Conditioning


DATE: November, 1991


CORPORATE NUMBER: 131208


SUBJECT: AIR CONDITIONER NOISE/VIBRATION (INSTALL BRACE KIT/POSSIBLE INERTIA RING PULLEY)

MODELS: 1988-91 C/K AND R/V TRUCKS WITH A/C AND 7.4L ENGINE


Some C/K and R/V trucks with 7.4L engines may exhibit a noise/vibration when the air conditioning is engaged.

This noise/vibration is the result of a resonance set up in the serpentine accessory drive system with air conditioning on.

SERVICE PROCEDURE:
This condition may be improved by installing a brace kit. The installation instruction included in the brace kit must be followed carefully. On some trucks, the addition of an inertia ring pulley may be required. On C/K models, refer to GMC Truck Bulletin 90-1B-111, published November 1991 (Corporate Bulletin # 061201) for new Suction Discharge Hose Assembly.


SERVICE PARTS INFORMATION:

Model Part
Year Number Description
1988-91 6553148 Pulley and Bearing
Assembly A/C Comp.
1988-90 10187643 Brace Kit-A/C Vibration
and Noise
1991 10187645 Brace Kit-A/C Vibration
and Noise

Parts are available at GMSPO.

WARRANTY INFORMATION:

1988-90 Labor Operation Number : T7286
Labor Time :.9 Hours (plus .2
Hrs. for skid
plate)
1991 Labor Operation Number: T7287
Labor Time :.4 Hours (plus .2
Hrs. for skid
plate)