The A/C compressor clutch is controlled by the body control module (BCM). The BCM sends the A/C request to the powertrain control module (PCM) via the Class 2 serial data circuit. This allows the PCM to manage idle quality, improve wide open throttle performance, and to protect the A/C system from excessively high and low pressures.

The PCM controlled air conditioning system uses a variable displacement compressor referred to as a V-5 compressor. The V-5 compressor meets the A/C requirements without cycling.

The BCM controlled air conditioning system consists of an A/C compressor clutch relay, an A/C compressor clutch, and an A/C refrigerant pressure sensor. The BCM) and the A/C select switch also input to the PCM through the Class 2 serial data circuit.

The A/C refrigerant pressure sensor is used to indicate high side pressures. This information is sent to the BCM from the PCM. The BCM uses this information to control the cooling fan operation, and the PCM controls the A/C compressor clutch operation. A malfunction in the A/C refrigerant pressure sensor circuit will set a DTC P0530. This will cause the PCM to disable the A/C compressor clutch compressor.

The PCM determines high and low pressures in the A/C system by the voltage signal received from the A/C refrigerant pressure sensor. This allows both the PCM and the BCM to protect the A/C system from excessively high and low pressures. If the A/C refrigerant pressure sensor voltage exceeds about 4.7 V, indicating a pressure of 428 psi, the PCM will disable the A/C compressor clutch. The A/C compressor clutch will remain disabled until the A/C refrigerant pressure sensor voltage falls below 1.98 V, indicating about 170 psi.

The BCM will allow the PCM to temporarily disable the A/C compressor clutch during the following conditions: