DELAYED A/C COOLING AFTER START UP. GMC Truck Jimmy

MODELS: 1988 MVAN AND S/T MODELS EQUIPPED WITH 2.5L ENGINES

The V5 is a variable displacement, five - cylinder compressor that automatically adjusts displacement to match air conditioning demand under all conditions. A control valve, located in the rear of the compressor, regulates the compressor capacity. The V5 compressor runs continuously in the A/C mode except during periods when overridden by A/C system control switches (Wide Open Throttle-WOT, etc.). Because the com- pressor is operating continuously, the engine will perform more smoothly due to lack of clutch cycling. Due to its variable displacement feature, special caution is necessary when diagnosing insufficient cooling conditions with the V5 compressor. Additionally, systems using the V5 compressor do not use a cycling pressure switch. Sections IB-3,4 and IB-41 of the 1988 M Van Service Manual and 1B-3 and 1B-35 of the S/T Service Manual make incorrect references to its use in systems using the V5. It is normal for liquid refrigerant to collect in the compressor crankcase during periods of shutdown, therefore, cooling action may be delayed up to two (2) minutes until the refrigerant is pumped from the crankease. If you experience a delay in cooling upon start-up beyond two (2) minutes, and the normal service manual procedure for A/C compressor clutch and electrical engine cooling fan operation has been accomplished, follow the procedure outlined below:

1. Operate the A/C system by setting to Norm A/C mode and high blower.

2. Be sure the compressor clutch has engaged and that the electrical engine cooling fan is operating.

3. Idle the engine for two (2) minutes with the A/C system operating.

4. If no cooling, run the engine at approximately 3000 rpm for one (1) minute with the A/C system operating.

5. If no cooling, change the mode control to Vent position for one (1) minute at idle.

6. Set A/C system back to Norm A/C mode, then run the engine at approximately 3000 rpm for one (1) minute with the A/C system operating.

7. If no cooling, drive the vehicle in a normal manner for five (5) minutes with the A/C operating.

8. If there is still no cooling, discharge the refrigerant system, inspect orifice tube for proper installation, evacuate, and recharge. The refrigerant should be introduced into the accumulator-dehydrator as rapidly as possible in liquid form. When using the small individual cans of refrigerant, the can should be turned upside down to accomplish the rapid recharge.

9. Check for proper cooling. If lack of cooling persists, remove and replace the compressor.

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.