Minimum Compressor On Time

Vehicles operating above 32 kmH (20 mph) will be controlled to a minimum ON time of 4 to 6 seconds before the HVAC control processor will allow the clutch to disengage. After a minimum ON time has expired, the HVAC control processor will request the PCM to disengage the A/C compressor clutch only if the low side temperature is below -2°C (28°F). After reaching this turn-off temperature, the HVAC control processor watts for the low side to reach a turn-on temperature of 10°C (50°F) and then repeats the cycle. During the compressor ON cycle, any of the following conditions will force the PCM to disengage the A/C compressor clutch:
^ Low battery voltage.
^ A/C refrigerant pressure sensor detects a low or high pressure condition.
^ Coolant temperatures above 126°C (259°F).

Except for Wide Open Throttle (WOT), all of these above conditions will keep the compressor OFF until the condition no longer exists. The WOT condition will keep the compressor OFF for a maximum of 20 seconds. On initial crank, the HVAC control processor will check for indications of liquid refrigerant which may have collected at the compressor. If found, the A/C compressor clutch will engage. After the engine has started, the clutch will disengage and waits for normal calibrations and parameters to activate the clutch.