A/C Request

When an A/C request is received by the PCM, the PCM engages the A/C clutch relay when all of the following conditions are met:

• the refrigerant pressure is not excessively high or low.
• the engine coolant temperature is not excessively high.
• the ambient air temperature is above approximately 0°C (32°F).
• a WOT condition is not present.
• the evaporator discharge air temperature is above approximately 1°C (33.8°F).

The PCM monitors the discharge pressure measured by the A/C pressure transducer. The PCM interrupts A/C compressor operation in the event the A/C pressure transducer indicates high system discharge pressures. It is also used to sense low charge conditions. If the pressure is below a predetermined value for a given ambient temperature, the PCM does not allow the A/C clutch to engage.