A/C - Noise/Vibration Upon Engagement

Number: 91-435-1D

Section: 1D

Date: OCT. 1991

Corporate Bulletin No.: 131208

ASE No.: A7

Subject:
AIR CONDITIONER NOISE/VIBRATION

Model and Year:
1988-91 C/K, R/V TRUCKS WITH 7.4. ENGINE

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

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





Correction:
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 Dealer Service Bulletin No. 90-382-1D for new Suction Discharge Hose Assembly.

Parts are currently available from GMSPO.

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)