CAMPAIGN: A/C DRIVE PULLEY AND COMPRESSION BELT REPLACE

Models: 1987-88 W7 GMC Forward - Trucks with Air Conditioning

TO: ALL AFFECTED DEALERS:

General Motors of Canada has determined that the air conditioning on certain 1987-88 W7 GMC Forward vehicles may stop due to an A/C compressor clutch seizure resulting from excessive high compressor speed. The high compressor speed prolongs the clutch engagement time, causing more heat buildup than the clutch can withstand.

To correct this condition, the existing drive pulley and compressor belt will be replaced with new updated parts.

VEHICLES INVOLVED:

Only the 13 vehicles listed below are involved:

1987 1988

J8DM7A1N5H3108376 J8DM7A1N7J3200210 J8DM7A1N4H3108613 J8DM7A1N3J3200222 J8DM7A1N4H3108644 J8DM7A1N4J3200438 J8DM7A1N7H3108668 J8DM7A1N2J3200468 J8DM7A1N4H3109017 J8DM7A1N3J3201192 J8DM7A1N1H3109024 J8DM7A1N9H3109062 J8DM7A1S1H3200946

All affected vehicles have been identified by the VIN listing provided to involved dealers with this bulletin. Any dealer not receiving a listing was not shipped any of the affected vehicles.

DEALER CAMPAIGN RESPONSIBILITY:

Dealers are to perform this campaign on all involved vehicles at no charge to owners, regardless of kilometres traveled, age of vehicle, or ownership, from this time forward.

Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service, you are to ensure the campaign correction has been made before selling or releasing the vehicle.

Owners of vehicles recently sold from your new vehicle inventory are to be contacted by the dealer, and arrangements made to make the required modification according to instructions contained in this bulletin.

CAMPAIGN PROCEDURE:

Refer to Section 4 of the Service Policies and Procedures Manual for the detailed procedure on handling Product Campaigns. Dealers are requested to complete the campaign on all transfers as soon as possible.

OWNER NOTIFICATION:

All owners of record at the time of campaign release are shown on the attached computer listing and have been notified by first class mail from General Motors. The listings provided are for campaign activity only and should not be used for any other purpose.

PARTS INFORMATION:

Parts required to complete this campaign will be shipped to affected dealers.

PARTS AND LABOUR CLAIM INFORMATION:

Credit for the campaign work performed will be paid upon receipt of a properly completed campaign claim card, RAPID terminal or DCS transmission in accordance with the following:

Repair Code Desciption Time Allowance ---------- -------------------------------- -------------- 1A Inspect for Model 17G - No Action Necessary . 3

2A Remove and Reinstall Drive Pulley and .7 Compressor Belt

Time allowance includes 0.1 hour for dealer administrative detail associated with this campaign. Parts credit will be based on dealer net plus 30% to cover parts handling.

SERVICE PROCEDURE:

The Air Conditioner (A/C) Crankshaft Drive Pulley and Compressor Belt have been redesigned for certain 1987-88 W7 series vehicles. The parts change was precipitated because the clutch assembly on the A/C compressor may seize when operated in certain RPM ranges. This A/C pulley and belt change affects only those units with Model No. 17G Compressors manufactured by Zexel (formerly known as Diesel Kiki) and/or that were factory installed, The Model Number is on the data label located on the rear of the compressor (See Figure 1). The new updated parts will reduce the A/C compressor speed and increase durability/reliability of die A/C compressor unit.

REQUIRED TOOLS & EQUIPMENT

3/8" Drive: - Ratchet Gong handle) Torque Wrench 6" Extension U-Joint 14 mm Shallow Socket 12 mm Shallow Socket 22 mm Open End or Combination Wrench Belt Tension Gauge

1. Inspect for involved compressor.

2. Check wheels and disconnect battery.

3. Remove the six (6) bolts and the drive pulley from the engine crankshaft damper pulley. (Figure 3)

4. Remove the compressor belt.

5. Install replacement drive pulley using new bolts as supplied in kit #94061289. Tightening torque: 34-46 lbs. ft. (46.1-62.4 N.m). (See Figure 3)

6. Loosen the lock nut of the tension pulley and adjust location for new compressor belt installation.

7. Install the new compressor belt supplied in kit and adjust belt tension using gauge. Tighten lock nut to retain correct belt tension. Belt tension: 120 lbs. (540 Newtons). (See Figure 4)

8. Reconnect the battery and unchock die wheels.

9. Install "Campaign Identification Label."

INSTALLATION OF CAMPAIGN IDENTIFICATION LABEL

Clean surface of radiator upper mounting panel and apply a Campaign Identification Label. Make sure the correct campaign number is inserted on the label. This will indicate that the campaign has been completed.

INSERT CAMPAIGN NUMBER INSERT DEALER CODE

Dear General Motors Customer:

General Motors of Canada has determined that the air conditioning on certain 1987-88 W7 GMC Forward vehicles may stop due to an A/C compressor clutch seizure as a result of high compressor speed. The high compressor speed prolongs the clutch engagement time, causing more heat buildup than the clutch can withstand.

To correct this condition, the existing drive pulley and compressor belt will be replaced with new updated parts. This service will be completed for you at no charge.

Please contact your GM dealer as soon as possible to arrange a service date. This letter identifies your vehicle. Presentation of this letter to your dealer will assist their Service personnel in completing the necessary coffection to your vehicle in the shortest possible time.

Further assistance, if required, may be obtained from our Customer Assistance Centre, toll free, by calling 1-800-263-3777, or if you live in Quebec, 1-800-263-7854.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products.

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.