GM Service Manual Online
For 1990-2009 cars only
HCM -- HVAC Sensors -- Outside Air Temp: The scan tool displays -40 to 60°C (-40 to 140°F). The output of the ambient air temperature sensor.

HCM -- HVAC Sensors -- Inside Air Temp: The scan tool displays -40 to 60°C (-40 to 140°F). The output of the inside air temperature sensor.

HCM -- HVAC Sensors -- Driver AC Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the LH A/C duct temperature sensor.

HCM -- HVAC Sensors -- Left HTR Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the LH HTR duct temperature sensor.

HCM -- HVAC Sensors -- Passenger AC Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the RH A/C duct temperature sensor.

HCM -- HVAC Sensors -- Passenger HTR Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the RH HTR duct temperature sensor.

HCM -- HVAC Sensors -- Driver Solar: The scan tool displays 0 to 50 counts. The solar load output of the LH sunload sensor.

HCM -- HVAC Sensor -- Passenger Solar: The scan tool displays 0 to 50 counts. The solar load output of the RH sunload sensor.

HCM -- HVAC System Data -- Commanded Blower: The scan tool displays 0 to 100%.

HCM -- HVAC System Data -- Selected Air Mode: The scan tool displays AUTO, Upper, Defog, Bi-Level, Heater or Defrost. The current operating mode of the HVAC system.

HCM -- HVAC System Data -- A/C Requested: The scan tool displays Yes or No. The message sent out on class 2 to the DIM when A/C is requested.

HCM -- HVAC System Data -- Coolant Temperature: The scan tool displays -40 to 120°C (-40 to 250°F). The information is received from the PCM on the class 2 communication link.

HCM -- HVAC System Data -- Pass HVAC Control: The scan tool displays 0 to 255 counts (0 to 5 volts). The position of the passenger temperature control is monitored.

HCM -- HVAC Door Positions -- Left Temp. Dr. Commanded: The scan tool displays 0 to 255 counts (0 to 5 volts). The desired position of the actuator.

HCM -- HVAC Door Positions -- Left Temp Dr Actual: The scan tool displays 0 to 255 counts (0 to 5 volts). The signal output from the feedback pot on the actuator.

HCM -- HVAC Door Positions -- Right Temp. Dr. Commanded: The scan tool displays 0 to 255 counts (0 to 5 volts). The desired position of the actuator.

HCM -- HVAC Door Positions -- Right Temp Dr Actual: The scan tool displays 0 to 255 counts (0 to 5 volts). The signal output from the feedback pot on the actuator.

HCM -- HVAC Door Positions -- HTR/DEF/AC Dr Commanded: The scan tool displays 0 to 255 counts (0 to 5 volts). The desired position of the actuator.

HCM -- HVAC Door Positions -- HTR/DEF/AC Dr Actual: The scan tool displays 0 to 255 counts (0 to 5 volts). The signal output from the feedback pot on the actuator.

HCM -- HVAC Door Positions -- Air Inlet Dr Commanded: The scan tool displays 0 to 255 counts (0 to 5 volts). The desired position of the actuator.

HCM -- HVAC Door Positions -- Air Inlet Dr Actual: The scan tool displays 0 to 255 counts (0 to 5 volts). The signal output from the feedback pot on the actuator.

HCM -- HVAC Door Calibrations -- Min Left Temp Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The minimum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Max Left Temp Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The maximum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Min Right Temp Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The minimum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Max Right Temp Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The maximum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Min HTR/DEF/AC Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The minimum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Max HTR/DEF/AC Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The maximum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Min Air Inlet Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The minimum travel range when driven to the stop.

HCM -- HVAC Door Calibrations -- Max Air Inlet Dr Pos: The scan tool displays 0 to 255 counts (0 to 5 volts). The maximum travel range when driven to the stop.

HCM -- Open/Short Data -- Outside Air Temp: The scan tool displays 0 to 255 counts (0 to 5 volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Inside Air Temp: The scan tool displays 0 to 255 counts (0 to 5 volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Left AC Duct Temp: The scan tool displays 0 to 255 counts (0 to 5 volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Left HTR Duct Temp: The scan tool displays 0 to 255 counts (0 to 5 volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Right AC Duct Temp: The scan tool displays 0 to 255 counts (0 to 5 volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Right HTR Duct Temp: The scan tool displays 0 to 255 counts (0 to 5 volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Left Solar Sensor: The scan tool displays 0 to 255 counts. The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- Open/Short Data -- Right Solar Sensor: The scan tool displays 0 to 255 counts. The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HCM -- HVAC Motors-- Left Temp Door Position: The scan tool displays Hot or Cold selections. The selection drives the actuator to its min or max stop.

HCM -- HVAC Motors -- Right Temp Door Position: The scan tool displays Hot or Cold selections. The selection drives the actuator to its min or max stop.

HCM -- HVAC Motors -- HTR/DEF/AC Door Position: The scan tool displays Defrost or Panel selections. The selection drives the actuator to its min or max stop.

HCM -- HVAC Motors -- Air Inlet Door Position: The scan tool displays Outside or Recirc. selections. The selection drives the actuator to its min or max stop.

HCM -- Miscellaneous Tests -- Instant OAT Update: The scan tool displays Commanded State: None or On. Updates the HCM outside air temperature input to the current raw value.

HCM -- Miscellaneous Tests -- Blower Motor: The scan tool displays Commanded State: None, Off or On. This function allows you to command the blower motor to its maximum (100%) or minimum (0%) speeds.

HCM -- Miscellaneous Tests--Second Head LED Driver: The scan tool displays Commanded State: None, 0% or 100%. This function commands the passenger temperature control to its minimum or maximum offset.

HCM -- Miscellaneous Tests -- HVAC Recalibration: The scan tool displays Commanded State: None or On. This function has the HCM relearn a new heater and A/C control.

HCM -- Set Options -- Afterblow: Allows the blower motor to run after the ignition is turned OFF.

HCM -- Temperature Offset: Allows for variation between driver set temperature and target (desired) system discharge temperature.

BCM -- A/C Information -- A/C Clutch (Actual): The scan tool displays On or Off. On is displayed when the PCM has energized the A/C clutch relay.

BCM -- A/C Information -- A/C Clutch (Desired): The scan tool displays On or Off. On is displayed when the HCM is requesting A/C system operation and the BCM has determined that none of the system performance limits are exceeded.

BCM -- A/C Information -- Control Head (Desired): The scan tool displays A/C On or A/C Off. A/C On is displayed when the HCM is requesting A/C system operation.

BCM -- A/C Information -- A/C Pressure: The scan tool displays 0 to 4000 kPa (0 to 580 psi). The output of the A/C pressure sensor provided by the PCM over the Class 2 communication link.

BCM -- A/C Information -- Pressure Status: The scan tool displays Low, Normal or High. Normal must be displayed to allow A/C operation.

BCM -- A/C Information -- Temperature Status: The scan tool displays Hot or OK. Hot is displayed when engine coolant temperature rises above 121°C (250°F). OK must be displayed to allow A/C operation.

PCM -- Engine Data 1 -- ECT: The scan tool displays -40 to 215°C (-40 to 420°F). The output of the engine coolant temperature sensor.

PCM -- Engine Data 2 -- ECT: The scan tool displays -40 to 215°C (-40 to 420°F). The output of the engine coolant temperature sensor.

PCM -- Engine Data 2 -- Commanded A/C: The scan tool displays On or Off. On is displayed when the PCM has energized the A/C clutch relay.

PCM -- Engine Data 2 -- A/C High Side Pressure: The scan tool displays 0 to 5 volts. The output of the A/C pressure sensor.

PCM -- Engine Data 2 -- A/C Press. Out Of Range: The scan tool displays Yes or No. Yes is displayed when the system pressure exceeds 2968 kPa (430 psi).

PCM -- Output Driver Data -- A/C Relay: The scan tool displays OK or Fault. Fault is displayed when an open or short is detected in the A/C CLU relay ground circuit.

PCM -- Engine Output Controls -- A/C Relay: The scan tool displays Off or On selections. This command allows you to turn the A/C relay OFF and ON.