Minimum Compressor on Time

Vehicles operating above 32 km/h (20 mph) are controlled to a minimum ON time of 4-6 seconds before the heater and A/C programmer will allow the clutch to disengage.

After the minimum ON time has expired, the heater and A/C programmer will request the Powertrain Control Module (PCM) to disengage the compressor clutch only if the low side temperature is below -2°C (28°F). After reaching this turn-off temperature, the heater and A/C programmer waits for the low side to reach a turn-on temperature of 10°C (50°F). The cycle then repeats. During the compressor ON cycle any of the following conditions will force the PCM to disengage the clutch:
^ DTC B1347-Repeated occurrences of an A/C low side temperature below -7°C (20°F) and/or the A/C low pressure switch is open.
^ DTC B1348-The A/C low pressure switch is open due to a catastrophic loss of refrigerant.
^ DTC B1350-The coolant temperature is above 126°C (259°F).

Except for the wide open throttle, any one of the above conditions will keep the compressor OFF until the condition no longer exists. The wide open throttle condition will keep the compressor OFF for a maximum of 20 seconds.

On the initial crank, the heater and A/C programmer will search for indications of liquid refrigerant which may have collected at the compressor. If liquid refrigerant is found, the A/C clutch engages. Shortly after the engine starts, the clutch disengages and waits for the normal calibrations and parameters to be met before signaling the clutch.