A/C - Delayed Cooling After Engine Start Up

87chevy29
GMC NUMBER: 88-T-59

GROUP: 1B - Air Conditioning

DATE: December, 1987

CORPORATE
NUMBER: 881201R
SUBJECT: DELAYED A/C COOLING AFTER ENGINE START UP

MODELS: 1988 M VAN AND S/T MODELS EQUIPPED WITH 2.5L ENGINES
The V5 is a variable displacement, fivecylinder 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 compressor 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 1B-3,4 and 1B-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 crankcase. 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.