Circuit Description
WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) monitors the high side refrigerant pressure through a A/C refrigerant pressure sensor. When the pressure is high the signal voltage is high. When the pressure is low the signal voltage is low. When pressure is high the PCM commands the cooling fans on. When pressure is too high or too low the PCM will not allow the A/C compressor clutch to engage. The PCM sends the A/C pressure data to the Dash Integration Module (DIM) over the Class 2 communication line. The DIM will not request A/C compressor clutch engagement if the A/C pressure is too high.