GM Service Manual Online
For 1990-2009 cars only
A/C Disengage History 1, 2, 3, or 4: The scan tool displays one of the following reasons why the powertrain control module (PCM) or engine control module (ECM) has disengaged the A/C compressor; None, System Voltage, Wide Open Throttle (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, RPM unstable, Launch Performance, 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 or 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 or 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 or 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 Relay Circuit Status: The scan tool displays the following message stating the circuit status of the A/C relay control circuit. The scan tool displays OK/Fault.

A/C Request Signal: The scan tool displays Yes/No. The scan tool displays Yes when the PCM or ECM receives a message to engage the A/C compressor clutch. The scan tool displays No when the PCM or 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 body control module (BCM).

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

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