Compressor Control Logic

The A/C compressor and engine cooling fan will be controlled by PCM/ECM/BCM control logic under the following conditions:

Coolant Temperature
^ Disabled if engine coolant temperature exceeds 117°C (242°F).
^ Enabled when coolant temperature is 114°C (237°F).

Low Intake Air Temperature
^ Disabled if intake air temperature goes below 2°C (36°F)
^ Enabled when intake air temperature is above 4°C (40°F).

A/C System Pressure

High
^ Disabled if A/C system pressure exceeds 2945 kPa (427 psi).
^ Enabled when A/C system pressure is 2069 kPa (300 psi).

Low
^ Disabled if A/C system pressure goes below 210 kPa (31 psi).
^ Enabled when A/C system pressure is 259 kPa (38 psi).

Engine Speed

High
^ Disabled if engine speed exceeds 6250 rpm.
^ Enabled if engine speed goes below 4750 rpm.

Low
^ Disabled if engine speed goes below 350 rpm.
^ Enabled if engine speed exceeds 600 rpm.

Throttle Position
^ Disabled if throttle position exceeds 95%.
^ Enabled when throttle position goes below 89% for 15 seconds.

Battery Voltage

High
^ Disabled if battery voltage exceeds 18 volts.
^ Enabled when battery voltage is less than 17 volts.

Low
^ Disabled if battery voltage goes below 10.5 volts.
^ Enabled when battery voltage exceeds 11 volts.

Evaporator Low Ambient Protection (ELAP)
The refrigerant temperature at the temperature sensor in the TXV controls cycling of the compressor clutch to prevent freezing of the evaporator core. The compressor is disabled when the temperature goes below 3°C (37°F) and vehicle speed is greater than 8 km/h (5 mph). The compressor Is enabled when the temperature exceeds 4°C (40°F). The minimum time off is 4 seconds.

Compressor Engagement During Engine Crank
The compressor clutch is engaged during engine cranking to cycle oil through the A/C system. The clutch is engaged when the engine speed is above 100 rpm.