Scan Tool Data Definitions

The HVAC Scan Tool Data Definitions contains a brief description of all HVAC related parameters available on the scan tool. The list is in alphabetical order. A given parameter may appear in any one of the data lists. In some cases, the parameter may appear more than once or in more than one data list in order to group certain related parameters together.

8 Digit GM Part Number: The scan tool displays the part number for service identification.

Auxiliary HVAC Control Assembly HVAC System Data - Auto Mode (front): The scan tool displays A/C/Bi-Level/Heater/Off. This value represents the discharge air mode of the front HVAC control module. The auxiliary HVAC control assembly will place the auxiliary mode actuator in the corresponding mode.

Auxiliary HVAC Control Assembly - HVAC System Data - Rear Blower: The scan tool displays RAM AIR, High, Med. High, Medium, or Low. Represents the auxiliary blower motor speed selected. RAM AIR indicates that the Auxiliary blower motor is OFF.

Auxiliary HVAC Control Assembly - HVAC System Data - Rear Mode: The scan tool displays A/C, Bi-Level, Heater, Auto, or Off. Represents the discharge air mode selected at the auxiliary HVAC control assembly.

Auxiliary HVAC Control Assembly - HVAC System Data - Rear Temp Offset: The scan tool displays -4 to +4. Represents the difference between the front and auxiliary air discharge temperatures selected, with -4 being the coolest possible temperature and +4 being the hottest temperature from the auxiliary air ducts.

Auxiliary HVAC Control Assembly - Outputs - Fan High: The scan tool displays Active/Inactive. Represents the state of the blower motor control circuit.

Auxiliary HVAC Control Assembly - Outputs - Fan Low: The scan tool displays Active/Inactive. Represents the state of the blower motor control circuit.

Auxiliary HVAC Control Assembly - Outputs - Fan Medium: The scan tool displays Active/Inactive. Represents the state of the blower motor control circuit.

Auxiliary HVAC Control Assembly - Outputs - Fan Medium High: The scan tool displays Active/Inactive. Represents the state of the blower motor control circuit.

Auxiliary HVAC Control Assembly - Outputs Mode Dr. Commanded: The scan tool displays 0-255 Counts. The desired position of the actuator.

Calibration ID: The scan tool displays the Calibration ID number for service identification.

Component Serial Number: The scan tool displays a 4 digit number.

DIM - 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 compressor clutch relay.

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

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

DIM - A/C Information - Clutch Voltage: The scan tool displays Low or Normal. Low is displayed when the battery voltage is low, such that A/C compressor clutch slippage is possible.

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

DIM - A/C Information - Evaporator Temp Status: The scan tool displays OK or Cold. Cold is displayed when evaporator temperature drops below 5°C (41°F).

DIM - A/C Information - Evaporator Temp.: The scan tool displays -40 to 215°C (-40 to 420°F). The output of the A/C low side thermistor.

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

DIM - Data - Steering Wheel Control: The scan tool displays 0-18 Volts. This value represents the input voltage the HVAC steering wheel controls.

DIM - Data - Steering Wheel Controls: The scan tool displays 0-110 Counts. This value represents the input to the HVAC control module from the HVAC steering wheel controls.

DIM - 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.

HVAC Control Module - HVAC Door Calibrations - Air Inlet Cal. Status: The scan tool displays Cal OK/High Req/Low Req. High Req or Low Req will be displayed when the actuator is being driven toward its maximum or minimum stop.

HVAC Control Module - HVAC Door Calibrations - HTR/DEF/AC Cal. Status: The scan tool displays Cal OK/High Req/Low Req. High Req or Low Req will be displayed when the actuator is being driven toward its maximum or minimum stop.

HVAC Control Module - HVAC Door Calibrations - Left Temp Cal. Status: The scan tool displays Cal OK/High Req/Low Req. High Req or Low Req will be displayed when the actuator is being driven toward its maximum or minimum stop.

HVAC Control Module - HVAC Door Calibrations - Rear Cal. Status: The scan tool displays Cal OK/High Req/Low Req. High Req or Low Req will be displayed when the actuator is being driven toward its maximum or minimum stop.

HVAC Control Module - HVAC Door Calibrations - Right Temp Cal. Status: The scan tool displays Cal OK/High Req/Low Req. High Req or Low Req will be displayed when the actuator is being driven toward its maximum or minimum stop.

HVAC Control Module - HVAC Door Calibrations - Air Inlet Dr Range: The scan tool displays 0-2500. The total number of pulses counted during the Recalibrate All Motors command.

HVAC Control Module - HVAC Door Calibrations - Door Move Counter: The scan tool displays 0-2500. The total number of pulses counted during the Recalibrate All Motors command.

HVAC Control Module - HVAC Door Calibrations - HTR/DEF/AC Dr Range: The scan tool displays 0-2500. The total number of pulses counted during the Recalibrate All Motors command.

HVAC Control Module - HVAC Door Calibrations - Left Temp Dr Range: The scan tool displays 0-2500. The total number of pulses counted during the Recalibrate All Motors command.

HVAC Control Module - HVAC Door Calibrations -Rear Temp Dr Range: The scan tool displays 0-2500. The total number of pulses counted during the Recalibrate All Motors command.

HVAC Control Module - HVAC Door Calibrations - Right Temp Dr Range: The scan tool displays 0-2500. The total number of pulses counted during the Recalibrate All Motors command.

HVAC Control Module - HVAC Door Positions - Air Inlet Dr Actual: The scan tool displays 0-255 Counts (0-5.00 Volts). The signal output from the feedback potentiometer on the recirculation actuator.

HVAC Control Module - HVAC Door Positions - Air Inlet Dr Commanded: The scan tool displays 0-255 Counts (0-5.00 Volts). The desired position of the recirculation actuator.

HVAC Control Module - HVAC Door Positions - HTR/DEF/AC Dr Actual: The scan tool displays 0-255 Counts (0-5.00 Volts). The signal output from the feedback potentiometer on the mode actuator.

HVAC Control Module - HVAC Door Positions - HTR/DEF/AC Dr Commanded: The scan tool displays 0-255 Counts (0-5.00 Volts). The desired position of the mode actuator.

HVAC Control Module - HVAC Door Positions - Left Temp Dr Actual: The scan tool displays 0-255 counts (0 to 5 volts). The signal output from the feedback potentiometer on the left air temperature actuator.

HVAC Control Module - HVAC Door Positions - Left Temp. Dr. Commanded: The scan tool displays 0-255 Counts (0-5.00 Volts). The desired position of the left air temperature actuator.

HVAC Control Module - HVAC Door Positions - Rear Temp Dr Actual: The scan tool displays 0-255 Counts (0-5.00 Volts). The signal output from the feedback potentiometer on the right air temperature actuator.

HVAC Control Module - HVAC Door Positions - Rear Temp Dr Commanded: The scan tool displays 0-255 Counts (0-5.00 Volts). The desired position of the right actuator.

HVAC Control Module - HVAC Door Positions - Right Temp Dr Actual: The scan tool displays 0-255 Counts (0-5.00 Volts). The signal output from the feedback potentiometer on the right air temperature actuator.

HVAC Control Module - HVAC Door Positions - Right Temp. Dr. Commanded: The scan tool displays 0-255 Counts (0-5.00 Volts). The desired position of the right actuator.

HVAC Control Module - 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.

HVAC Control Module - HVAC Sensors - Left AC Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the upper left air temperature sensor.

HVAC Control Module - HVAC Sensors - Left Duct Temp Desired: The scan tool displays - 18 to 120°C (0 to 250°F). The target LH duct temperature that the HVAC system is trying to achieve.

HVAC Control Module - HVAC Sensors - Left HTR Duct Temp: The scan tool displays - 40 to 150°C (-40 to 300°F). The output of the lower left air temperature sensor.

HVAC Control Module - HVAC Sensors - Left Solar: The scan tool displays 0-255 counts. The solar load output of the sunload sensor assembly.

HVAC Control Module - HVAC Sensors - Outside Air Temp: The scan tool displays - 40 to 60°C (-40 to 140°F). The output of the outside air temperature sensor.

HVAC Control Module - HVAC Sensors - Rear Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the upper right air temperature sensor.

HVAC Control Module - HVAC Sensors - Rear Duct Temp Desired: The scan tool displays - 18 to 120°C (0 to 250°F). The target RH duct temperature that the HVAC system is trying to achieve.

HVAC Control Module - HVAC Sensors - Right AC Duct Temp: The scan tool displays -40 to 150°C (-40 to 300°F). The output of the upper right air temperature sensor.

HVAC Control Module - HVAC Sensors - Right Duct Temp Desired: The scan tool displays - 18 to 120°C (0 to 250°F). The target RH duct temperature that the HVAC system is trying to achieve.

HVAC Control Module - HVAC Sensors - Right HTR Duct Temp: The scan tool displays - 40 to 150°C (-40 to 300°F). The output of the lower right air temperature sensor.

HVAC Control Module - HVAC Sensors - Right Solar: The scan tool displays 0-255 counts. The solar load output of the sunload sensor assembly.

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

HVAC Control Module - HVAC System Data - Commanded Blower: The scan tool displays 0 to 100%. The blower speed being requested by the HVAC control module.

HVAC Control Module - 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.

HVAC Control Module - HVAC System Data - Left Program Number: The scan tool displays 0-255 counts. This value will vary, depending on the air delivery mode and the air discharge temperature selected by the driver.

HVAC Control Module - HVAC System Data - Load Reduction Active: The scan tool displays Yes or No. Yes will be displayed when a low battery condition is detected and one or more accessories (blower motor, A/C compressor clutch, etc.) have been disabled in order to reduce the electrical load.

HVAC Control Module - HVAC System Data - Rear Program Number: The scan tool displays 0-255 counts. This value will vary, depending on the air delivery mode and the air discharge temperature selected.

HVAC Control Module - HVAC System Data - Right Program Number: The scan tool displays 0-255 counts. This value will vary, depending on the air delivery mode and the air discharge temperature selected by the passenger.

HVAC Control Module - HVAC System Data - Selected Air Mode: The scan tool displays: Auto/Upper/Bi-Level/Floor/Defog/Defrost. This data indicates the discharge air mode selected. The positions are displayed as follows:
^ AUTO - The HVAC Control Module controls all HVAC air flow.
^ UPPER - The air flows from the 4 upper vents.
^ BI-LEVEL - The air flows from the 4 panel vents and the 2 floor vents.
^ FLOOR - The air flows from the 2 floor vents.
^ DEFOG - The air flows from the defrost vent at the top of the instrument panel and the 2 floor vents.
^ DEFROST - The air flows from the defrost vent at the top of the instrument panel.

HVAC Control Module - HVAC System Data - System Program Number: The scan tool displays 0-255 counts. This value will vary, depending on the air delivery mode and the air discharge temperatures selected by the driver and passenger.

HVAC Control Module - HVAC System Data - Vehicle Speed: The scan tool displays 0-249 km/h/0-155 mph. This value is used to calculate the outside air temperature when the vehicle is moving.

HVAC Control Module - Open/Short Data - Inside Air Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HVAC Control Module - Open/Short Data - Left AC Duct Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HVAC Control Module - Open/Short Data - Left HTR Duct Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

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

HVAC Control Module - Open/Short Data - Outside Air Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HVAC Control Module - Open/Short Data - Rear Duct Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HVAC Control Module - Open/Short Data - Right AC Duct Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

HVAC Control Module - Open/Short Data - Right HTR Duct Temp: The scan tool displays 0-255 Counts (0-5.00 Volts). The status of the sensor signal circuit is monitored. 0 counts indicates a short to ground, 255 counts indicates an open circuit.

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

Julian Date of Build: The scan tool displays a 3 digit number. An example would be 256.256 is September 12, which is day 256 based on the Julian Calendar.

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

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

PROM ID: The scan tool displays the PROM ID number for service identification.

Year Module Built: The scan tool displays a 4 digit number representing the year in which the module was built.