Controls

An electronic A/C pressure switch is mounted on the discharge line (high side) of the A/C compressor suction/discharge hose assembly. Its output to the PCM is variable and is dependent upon pressure inside the line.

This sensor operates like other 3-wire sensors. The PCM applies a 5.0 volt reference and a ground for the sensor. Changes in the A/C refrigerant pressure will cause the A/C pressure sensor input to the PCM to vary. The PCM monitors the A/C refrigerant pressure signal circuit and can determine when the signal is outside of the range of the sensor. When the signal is out of range (high or low) for a period of time, the Body Control Module (SBM) will set DTC B1324.

The PCM communicates the status of the A/C system pressure to the body control module (SBM) via Class 2 serial data. A higher pressure results in a higher voltage output. The PCM monitors the A/C pressure to:

^ Disengage the A/C clutch if the pressures are high -2968 kPa (430 psi).
^ Disengage the A/C clutch if pressures are too low -below 255 kPa (37 psi).