CAMPAIGN: A/C DRIVE PULLEY AND COMPRESSOR BELT REPLACEMENT

SUBJECT: A/C DRIVE PULLEY AND COMPRESSOR BELT REPLACEMENT

MODELS: 1987-91 W6/W7 GMC FORWARD - CHEVROLET TILTMASTER TRUCKS WITH AIR CONDITIONING

General Motors has learned that the air conditioning on certain 1987-91 W6/W7 GMC Forward - Chevrolet Tiltmaster 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

Involved are certain 1987-91 W6/W7 GMC Forward - Chevrolet Tiltmaster vehicles built within the following VIN breakpoints:

Model Year Make From Through ---- ---------- -------- --------- 1987 GMC H3107336 H3109003 Chevrolet H3107354 H3109002 1988 GMC J3100020 J3201623 Chevrolet J3100143 J3201243 1989 GMC K3100071 K3201450 Chevrolet K3100025 K3201402 1990 GMC L3100910 L3202529 Chevrolet L3100840 L3202405 1991 GMC M3102563 M3200684 Chevrolet M3102566 M3200550

The specific vehicles involved in this campaign have been identified by Vehicle Identification Number Computer Listings. These listings are furnished to all involved dealers with the campaign bulletin.

DEALER CAMPAIGN RESPONSIBILITY

Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of mileage, age of vehicle, or ownership, from this time forward. Dealers are to correct all affected vehicles in new and used vehicle stock prior to their sale.

Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service in the future, you should take the steps necessary to ensure the campaign correction has been made before reselling 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 correction according to instructions contained in this bulletin.

If the name and address of the owner of an involved vehicle was unavailable to GMC Truck Division at the time of campaign initiation, the dealer must determine the owner's name and address from the dealership sales records. Please provide this information directly on the second copy of the listing next to the applicable VIN so that our records may be updated and the appropriate notification mailed to the owner. This second copy should then be submitted to the address listed below in the previously supplied yellow campaign envelopes.

GMC Truck Division General Motors Corporation 101 Union Street Plymouth, Michigan 48170

OWNER NOTIFICATION

Owners will be notified of this campaign on their vehicles by GMC Truck Division (see copy of owner letter included with this bulletin). A listing of owner names and addresses has been furnished to the involved dealers to enable dealers to follow up with owners involved in this campaign. This listing may contain owner names and addresses obtained from State Motor Vehicle Registration records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to this campaign.

SERVICE INFORMATION

The Air Conditioner (A/C) Crankshaft Drive Pulley and Compressor Belt have been redesigned for certain 1987-91 W6 and 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 No. 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 the A/C compressor unit.

SERVICE PROCEDURE REQUIRED TOOLS & EQUIPMENT --------------------------- 3/8" Drive: Ratchet (long handle) Torque Wrench 6" Extension U-Joint 14 mm Shallow Socket 12 mm Shallow Socket

22 mm Open End or Combination Wrench Belt Tension Gage

1. Inspect for involved compressor.

2. Chock 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 gage. Tighten lock nut to retain correct belt tension. Belt tension: 120 lbs. (540 Newtons). (See Figure 4)

8. Reconnect the battery and unchock the wheels

9. Install "Campaign Identification Label".

PARTS INFORMATION

Parts should be ordered directly from isuzu Parts Distribution Network (AIPDN). Parts may also be obtained from General Motors Service Parts Opera- tion (GMSPO) on an order type ISC.

Part Number Description Quantity ------- ---------------------- --------- 94061289 Kit 1

Kit Consists of the following:

94061268 Pulley, A/C Drive 1 94061269 Belt, A/C Compressor 1 94001918 Bolts, A/C Ddve Pulley 6 (MIO x 1.25, L = 30 mm)

WARRANTY INFORMATION

Dealers should submit a warranty claim on each vehicle completed under this campaign.

Labor Operation *Time Trouble Number Description Allowance Code --------- ----------------- ---------- ----- V6650 Inspect for Model 0.2 Hrs. 96 17G-No action 1 necessary

V6651 Remove and rein- 0.6 Hrs. 96 stall drive pulley and compressor belt

*For dealer to receive Administrative Time Allowance associated with this campaign, add 0.1 hour to the Labor Operation Time Allowance.

CAMPAIGN IDENTIFICATION LABEL

Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Bulletin will require a 'Campaign Identification Label.' Each label provides a space to include the campaign number and five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or ball point pen.

Each "Campaign Identification Label" is to be located on the cab inner panel in an area which will be visible when the vehicle is brought in for periodic servicing by the owner.

Apply "Campaign Identification Label" only on a clean, dry surface.

ADMINISTRATIVE PROCEDURE

Procedures covering this campaign are outlined in Section V of your dealership's "GM Truck Claims Processing Manual" #P8919.

Dear General Motors Truck Owner:

General Motors has learned that the air conditioning on your 1987-91 W6/W7 GMC Forward - Chevrolet Tiltmaster vehicle 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.

Instructions for making this correction have been sent to your GM dealer. Please contact your dealer as soon as possible to arrange a service date. Ask your dealer if you wish to know how much time will be needed to schedule, process and repair your vehicle.

The enclosed postage paid owner reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction to your vehicle in the shortest possible time. If you have sold or traded your vehicle, please furnish us the complete name and address of the person to whom you sold or traded your vehicle and return the card to us.

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.