GM Service Manual Online
For 1990-2009 cars only
A/C Disengage Reason: The scan tool displays one of the following reasons why the PCM/ECM has disengaged the a/c compressor; None, System Voltage, WOT, CKP, Learn Active, Engine Run Time, Coolant Hot, Anti Stall, A/C Pressure, Engine Speed, Trans Engine Speed, A/C Pressure Sensor, Low Voltage, High Voltage, Outside Air, Temp, A/C Switched Off.

A/C High Side Pressure Sensor: The scan tool displays 0-3450 kPa (0-500 psi). The voltage applied to the PCM/ECM input from the A/C refrigerant pressure sensor is converted to a pressure value.

A/C High Side Pressure Sensor: The scan tool displays 0-5 volts. The voltage applied to the PCM/ECM input for the A/C refrigerant pressure sensor.

A/C Off for WOT: The scan tool displays the high throttle disable of the a/c compressor.

A/C Pressure Disable: The scan tool displays the status of the a/c high side pressure sensor. The scan tool displays Active/Inactive.

A/C Relay Command: The scan tool displays On/Off. The scan tool displays the control decision for the compressor clutch relay output as determined by the PCM/ECM.

A/C Relay Circuit History: The scan tool displays the following message stating the history status of the a/c relay control circuit. The scan tool displays OK/Open/Short.

A/C Request Signal: The scan tool displays Yes/No. The scan tool displays Yes when the PCM/ECM receives a message to engage the A/C compressor clutch. The scan tool displays No when the PCM/ECM receives a message to disengage the A/C compressor clutch.

A/C Request Switch: The scan tool displays On/Off. The a/c request switch shows current status of the a/c request switch function on the BCM.

ECT Sensor: The scan tool displays -40 to +215°C (-40 to +419°F). The voltage applied to the PCM/ECM input from the engine coolant temperature sensor is converted to a temperature value.

FC Relay 1 Command: The scan tool displays the command status of the PCM/ECM to relay 1. The scan tool displays On/Off.

FC Relay 2 and 3 Command: The scan tool displays the command status of the PCM/ECM to relays 2 and 3. The scan tool displays On/Off.

Ignition 1 Signal: The scan tool shows available voltage at the PCM/ECM. The scan tool displays 0-12 volts.

Outside Air Temp Sensor: The voltage applied to the BCM input for the outside air temperature sensor. The scan tool displays 0-5 volts.