GM Service Manual Online
For 1990-2009 cars only

Panel Discharge Temperature Sensors

The panel discharge temperature sensors are used to monitor the discharge temperature of the air conditioning system. There are two sensors which monitor the driver and passenger air conditioning temperature. The IPM monitors these sensors and adjusts the discharge temperatures accordingly. These sensors are located in the behind the outer instrument panel vents in the ducts.

Heater Temperature Sensors

The heater temperature sensors are used to monitor the discharge temperature of the air flowing out of the heater ducts. There are two sensors which monitor the driver and passenger the heater discharge temperatures. The IPM monitors these sensors and adjusts the discharge temperatures accordingly. These sensors are located within the air passages in the closeout sound insulators.

A/C Compressor Control Relay

The A/C compressor control relay cycles the compressor on and off by energizing/de-energizing the compressor clutch coil. When the ignition is on, 12 volts is supplied to the relay common contact and one coil terminal. The second coil terminal is grounded by the PCM when the driver selects A/C or defrost mode, and all other requirements are met. When the relay is energized current passes through the relay contacts which energizes the compressor clutch coil.