A/C - Compressor Moan, Vibration or Noise
GMC NUMBER: 89-1B-118GROUP: 1B-Air Conditioning
DATE: December, 1989
CORPORATE NUMBER: 961205
SUBJECT:
R4 A/C COMPRESSOR MOAN/VIBRATION/NOISE
MODEL:
ALL 1987-89 LIGHT TRUCKS WITH SERPENTINE BELT
Some 1987-89 light trucks, equipped with an R4 A/C compressor, may develop a condition described as a moan, vibration or noise when the A/C compressor is engaged. To address this condition Harrison Radiator has released a revised R4 A/C compressor (P/N 12338629) for truck applications listed below. The new compressor can be identified by a new model label. The new label has the model number printed in black with an orange background. In prior years the model number has been black with a gray/silver background.
IMPORTANT:
The revised compressor alone will not solve all customer A/C noise comments. It is essential that the revised compressor be used only after the following noise abatement procedures have been employed.
* Check A/C system for grounding (hoses/pipes hitting hoses/pipes, body or engine)
* Check mounting bolts for being loose, missing or a blind hole
* Check drive belt for debris in the grooves or wear
Check that a brace kit has been installed from one of the following bulletins: 88-T-56 (corporate # 831203), 88-T-132 (corporate # 831209R), 88-T-152 (corporate # 821202R) and 89-T-02 (corporate # 831211R). All are filed in group 1B.
NOTICE:
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 stem will be severely restricted. If there is no evidence of leakage when the old compressor is removed: Drain oil from the old compressor. Measure the amount removed; if less than 1 oz. is drained from the old compressor, add 2 oz. to the new compressor. If more than 1 oz. is drained from the old compressor, add the same amount to the new compressor.
IMPORTANT:
The R4 service compressor (P/N 12338629) is shipped with a green fan switch (located on the rear of the compressor). The switch is used only on C/K trucks, however, the switch does not have to be removed when this service compressor is used on other trucks as it does not interfere with the operation of the compressor. The 7.4L G Van uses a red fan switch that must be transferred when this service compressor is used.
On the following trucks the compressor can be installed as shipped.
MODEL ENGINE
1988 - 89 C/K ALL ENGINES
1989 R/V 5.7L, 7.4L
1987 - 89 G VAN 5.0L, 5.7L
1988 - 89 S/T 4.3L
On the following trucks before installing the compressor one or all of the following will have to be transferred: pulley, coil and/or clutch. Compare compressors before installation to assure that the electrical terminal is in the correct position.
MODEL ENGINE
1987 - 89 S/T 2.8L
1987 - 89 G VAN 4.3L
1987 - 89 M VAN 4.3L
1989 G VAN 7.4L
Parts are expected to be available on December 4, 1989. Until then, normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be canceled as incorrectly ordered while the 400 control is in place.
Labor Op: D4440
Labor lime: Use applicable time from the Labor Time Guide.
Policy: A (Requires Zone Authorization)