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 8 digit alphanumeric module part number.

A/C Clutch (Actual): The scan tool displays On/Off. On is displayed when the powertrain control module (PCM) has energized the A/C compressor clutch relay.

A/C Clutch (Desired): The scan tool displays On/Off. On is displayed when the instrument panel integration module (IPM) is requesting A/C system operation and the DIM has determined that none of the system performance limits are exceeded.

A/C Requested: The scan tool displays Yes/No. Display indicates the class 2 message sent to the powertrain control module (PCM) when A/C is requested.

Accum Fault - Compressor: The scan tool displays Active/Inactive. Display indicates a defined period of time that the compressor is active with out an exhaust cycle.

Accum Fault -- Exhaust: The scan tool displays Active/Inactive. Display indicates a defined period of time the exhaust is active with out a compressor cycle.

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.

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

Air Inlet Dr Actual: The scan tool displays 0-255 counts. The signal output from the feedback potentiometer on the recirculation actuator.

Air Inlet Dr Commanded: The scan tool displays 0-255 counts. The desired position of the recirculation actuator.

Auto Mode (Front): The scan tool displays A/C/Bi-Level/Heater/Off. This value represents the discharge air mode of the instrument panel integration module (IPM). The rear heater and A/C control will place the auxiliary mode actuator in the corresponding mode.

Battery Reconnect: The scan tool displays On/Off. When the module senses a battery reconnect the scan tool will display On.

Battery Saver - History: The scan tool displays On/Off. Display indicates the state of the battery rundown protection feature.

Battery Voltage: The scan tool displays 0-20  volts. The scan tool displays the voltage as received on the battery positive voltage circuit of the Module or the 72-08 battery voltage message from the dash integration module (DIM) over class 2 line.

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

Cigar Lighter Relay: The displays On/Off. Display indicates the commanded state of the cigar lighter relay.

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.

Commanded Blower: The scan tool displays 0 to 100%. The blower speed being requested by the instrument panel integration module (IPM).

Component Serial #8 - 11: The scan tool displays an alphanumeric number. Display indicates digits 8 -- 11 of the component serial number.

Component Serial #12: The scan tool displays an alphanumeric number. Display indicates digit 12 of the component serial number.

Component Serial #13 - 16: The scan tool displays an alphanumeric number. Display indicates digits 13 -- 16 of the component serial number.

Component Serial #17 - 18: The scan tool displays an alphanumeric number. Display indicates digits 17 -- 18 of the component serial number.

Component Serial Number: The scan tool displays a 8 digit alphanumeric number. Display indicates the first 8 digits of the component serial number.

Control Head (Desired): The scan tool displays On or Off. On is displayed when the instrument panel integration module (IPM) is requesting A/C system operation.

Control Power: The scan tool displays On/Off. Display indicates the state of control power.

Coolant Temperature: The scan tool displays -40 to +120°C (-40 to +250°F). The information is received from the powertrain control module (PCM) on the class 2 serial communication line.

CTD State: The scan tool display varies. Display indicates the state of the content theft deterrent system.

Daytime Running Lamp: Scan tool displays On/Off. Display indicates the commanded state of the daytime running lamp relay.

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

Driver Door Jamb Switch: The scan tool displays On/Off. Display indicates the state of the driver door jamb switch.

ELC Compressor Active: The scan tool displays Yes/No. The scan tool will display Yes when the vehicle trim height is below a preset value. The ALC Compressor inflates the rear airlift shocks until the vehicle reaches the desired trim height. When the vehicle is at the desired trim height, the scan tool will display No.

ELC Exhaust Solenoid Active: The scan tool displays Yes/No. The scan tool will display Yes when the vehicle trim height is above a preset value. The ALC Exhaust Solenoid deflates the rear airlift shocks until the vehicle reaches the desired trim height. When the vehicle is at the desired trim height, the scan tool will display No.

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

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

Filtered Position Value: The scan tool displays 0-255 counts. This parameter is not used and the scan tool will always display 0 counts.

Flash to Pass Switch: The scan tool displays On/Off. Display indicates the state of the flash to pass switch.

Front Fog Lamp Switch: The scan tool displays On/Off. Display indicates the state of the front fog lamp switch.

Front Foglamp Relay: The scan tool displays On/Off. Display indicates the commanded state of the front fog lamp relay.

Fuel Door Release Relay: The scan tool displays On/Off. Display indicates the commanded state of the fuel door release relay.

Fuel Door Release Sw: The scan tool displays On/Off. Display indicates the state of the fuel door release switch.

Hazard Lamp Switch: The scan tool displays On/Off. Display indicates the state of the hazard lamp switch.

Head Lamp Switch: The scan tool displays On/Off. Display indicates the state of the headlamp switch.

High Beam Output: The scan tool displays On/Off. Display indicates the commanded state of the high beam output.

High Beam Output (Flash to Pass): The scan tool displays On/Off. Display indicates the commanded state of the flash to pass control.

Hood Ajar Switch: The scan tool displays On/Off. Display indicates the state of the hood ajar switch.

Hood Jamb Switch: The scan tool displays On/Off. Display indicates the state of the hood jamb switch.

Horn Output: The scan tool displays On/Off. Display indicates the commanded state of the horn output.

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.

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

HTR/DEF/AC Dr Actual: The scan tool displays 0-255 counts. The signal output from the feedback potentiometer on the mode actuator.

HTR/DEF/AC Dr Commanded: The scan tool displays 0-255 counts. The desired position of the mode actuator.

HTR/DEF/AC Temp Door 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.

HUD Dimming: The scan tool displays On/Off. Display indicates the state of the head up display dimming feature.

Ignition 1: The scan tool displays Active/Inactive. Display indicates the status of the discrete ignition positive voltage signal.

Ignition 3: The scan tool displays Active/Inactive. Display indicates the status of the discrete ignition positive voltage signal.

Ignition 3 Input: The scan tool displays Active/Inactive. The scan tool displays Active when the Ignition 3 input (run) circuit of the module receives a battery voltage signal from the ignition switch.

Ignition Accessory: The scan tool displays Active/Inactive. The scan tool displays Active when only the Accessory and unlock circuits of the dash integration module (DIM) receives a battery voltage signal from the ignition switch.

Ignition Counter: The scan tool displays 0-50. The module counts each time the ignition switch is cycled.

Ignition Crank/Run: The scan tool displays Active/Inactive. The scan tool displays Active when the Crank/Run, Run and Unlock circuits of the dash integration module (DIM) receives a battery voltage signal from the ignition switch.

Ignition Switch: The scan tool displays Accy/Crank/Off/RAP/RAP-Unlock/Run/Unlock. The scan tool displays Accy when the accessory and unlock circuits of the dash integration module (DIM) receives a battery voltage signal from the ignition switch. The scan tool displays Crank when the Crank/Run, Run and Unlock circuits of the DIM receives a battery voltage signal from the ignition switch. The scan tool displays Off when none of the power moding circuits of the DIM receive a battery voltage signal from the ignition switch. The scan tool displays RAP (Retained Accessory Power) when RAP is active and none of the power moding circuits of the DIM receive a battery voltage signal from the ignition switch. The scan tool displays RAP-Unlock when RAP is active and the Ign. Unlock circuit of the DIM receives a battery voltage signal from the ignition switch. The scan tool displays Run when all of the power moding circuits of the DIM receive a battery voltage signal from the ignition switch. The scan tool displays Unlock when the Unlock circuit of the DIM receives a battery voltage signal from the ignition switch.

Ignition Unlock: The scan tool displays Active/Inactive. The scan tool displays Active when only the Unlock circuit of the dash integration module (DIM) receives a battery voltage signal from the ignition switch.

Incandescent Dim #1: The scan tool displays On/Off. Display indicates the state of the incandescent lamp ground circuit.

Inside Air Temp: The scan tool displays -40 to 60°C (-40 to 140°F) or volts/counts in the open/short data list. Display indicates the output of the inside air temperature sensor.

Interior Dim Pot: The scan tool displays 0-255 counts. Display indicates the amount of interior dimming requested.

Interior Lamp Input: The scan tool displays On/Off. Display indicates the state of the interior lamp input.

Interior Lamp Switch: The scan tool displays OFF/AUTO/ON. Display indicates the position of the interior lamp switch -- AUTO is the normal operating range.

Interior Temp Sensor Fan: The scan tool displays On/Off. Display indicates the commanded state of the interior temp sensor fan.

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.

Key In Ignition: The scan tool displays Yes/No. The scan too displays Yes when the key is in the ignition and the instrument panel integration module (IPM) receives a signal from the ignition switch.

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

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

Left 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.

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.

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

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

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.

Left Rear Door Jamb Switch: The scan tool displays On/Off. Display indicates the state of the left rear door jamb switch. On indicates the door is open and Off indicates the door is closed.

Left Solar: The scan tool displays 0-255 counts. Display indicates the solar load output of the sunload sensor assembly.

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

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.

Left Temp Dr Range: The scan tool displays 0-2500. Display indicates the total number of pulses counted during the Recalibrate All Motors command.

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

Left Temp Dr Commanded: The scan tool displays 0-255 counts (0-5.00 volts). Display indicates the desired position of the left air temperature actuator.

Leveling Sensor Feed: The scan tool displays volts. Display indicates the voltage feed to the suspension position sensor.

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.

Load Shed LVL. 1 R Defog: The scan tool displays On/Off. The scan tool displays Off unless the RIM has entered level 1 of load management and commanded the rear defrost OFF.

Load Shed LVL. 2 R Defog: The scan tool displays On/Off. The scan tool displays Off unless the RIM has entered level 2 of load management and commanded the rear defrost OFF.

Low/High Beam Output: The scan tool displays On/Off. Display indicates the commanded state of the low beam relay.

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

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

Overhead Lamps Output: The scan tool displays On/Off. Display indicates the commanded state of the overhead lamps.

Park (BTSI) Relay: The scan tool displays On/Off. Display indicates the commanded state of the park relay.

Park Brake Relay - A: The scan tool displays On/Off. Display indicates the state that the rear integration module (RIM) is commanding the park brake relay A.

Park Brake Relay - B: The scan tool displays On/Off. Display indicates the state that the rear integration module (RIM) is commanding the park brake relay B.

Park Key Lock Relay: The scan tool displays On/Off. Display indicates the commanded state of the lock cylinder relay.

Park Lamp: The scan tool displays On/Off. Display indicates the state of the park lamp switch.

Park Lamp Relay Output: The scan tool displays On/Off. Display indicates the commanded state of the park lamp relay.

Pass. Door Jamb Switch: The scan tool displays On/Off. Display indicates the state of the passenger door jamb switch.

Position Lamp Relay: The scan tool displays On/Off. Display indicates the commanded state of the standing lamp relay.

Power Mode Change: The scan tool displays On/Off. The scan tool Displays On when the power source has changed from ON, IGN, or RAP.

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

Progress Fault - Compressor: The scan tool displays Active/Inactive. Display indicates a defined period of time that the compressor is active and no change is detected by the suspension position sensor.

Progress Fault - Exhaust: The scan tool displays Active/Inactive. Display indicates a defined period of time the exhaust is active and no change is detected by the suspension position sensor.

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

RAP Output: The scan tool displays On/Off. The scan tool displays On until the ignition switch is placed into the Off position and a passenger compartment door is opened or when retained accessory power (RAP) is disabled, then Off is displayed.

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

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.

Rear Defog Relay: The scan tool displays On/Off. Display indicates the commanded state of the rear defog relay.

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

Rear Duct Temp (Open/Short Data): 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.

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.

Rear Fog Lamp Relay: The scan tool displays On/Off. Display indicates the commanded state of the rear fog lamp relay.

Rear Fog Lamp Switch: The scan tool displays On/Off. Display indicates the status of the rear fog lamp switch.

Rear Mode: The scan tool displays A/C, Bi-Level, Heater, Auto, or Off. Display Represents the discharge air mode selected at the rear heater and A/C control.

Rear Parking Aid - 1: The scan tool displays Active/Inactive. Display indicates the state of the level 1 rear parking aid.

Rear Parking Aid - 2: The scan tool displays Active/Inactive. Display indicates the state of the level 2 rear parking aid.

Rear Parking Aid - 3: The scan tool displays Active/Inactive. Display indicates the state of the level 3 rear parking aid.

Rear Parking Aid Input: The scan tool displays On/Off. Display indicates the state of the rear parking aid input.

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.

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

Rear Temp Dr Actual: The scan tool displays 0-255 counts. The signal output from the feedback potentiometer on the right air temperature actuator.

Rear Temp Dr Commanded: The scan tool displays 0-255 counts. The desired position of the right actuator.

Reverse Lamp Relay: The scan tool displays On/Off. Display indicates the commanded state of the reverse lamp relay.

Reverse Lockout Drive: The scan tool displays On/Off. Display indicates the commanded state of the reverse lockout relay.

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

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

Right 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.

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

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

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

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.

Right Rear Door Jamb Switch: The scan tool displays On/Off. Display indicates the status of the right rear door jamb switch.

Right Solar: The scan tool displays 0-255 counts. Display indicates the solar load output of the sunload sensor assembly.

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

Right Temp Door Range: The scan tool displays 0-2500 pulses. Display indicates the total number of pulses counted during the Recalibrate All Motors command.

Right Temp Dr Actual: The scan tool displays 0-255 counts. Display indicates the signal output from the feedback potentiometer on the right air temperature actuator.

Right Temp Dr Commanded: The scan tool displays 0-255 counts (0-5.00 volts). Display indicates the desired position of the right actuator.

Select Air Mode: The scan tool displays: Auto/Upper/Bi-Level/Heater/Defog/Defrost. Display indicates the indicates the discharge air mode selected. The positions are displayed as follows:

Steering Wheel Control Feed Voltage: The scan tool displays 0-25 volts. Display indicates the voltage input to the steering wheel controls.

Steering Wheel Control: The scan tool displays 0-18 volts. Display indicates the value represented by the input voltage the HVAC steering wheel controls.

Steering Wheel Controls A/D: The scan tool displays 0-25 counts. This value represents the input voltage the HVAC steering wheel controls.

Suspension Position Sensor: The scan tool displays 0-5.0 volts. The position sensor is a variable resistor which changes with vehicle trim height. The ELC system uses this voltage reading to determine different road and driving conditions. The ELC system adjusts the damping level in each shock absorber based upon the voltage level received back from all four position sensors.

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.

TCS Switch: The scan tool displays On/Off. Display indicates the state of the traction control switch.

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.

Theft Lighting: The scan tool displays On/Off. Display indicates the commanded state of the theft lighting feature.

Trailer Detection Input: The scan tool displays On/Off. Display indicates the state of the trailer detection input.

Trans Fluid Temp: The scan tool displays -40 to 120°C (-40 to 250°F). Display indicates the temperature of the transmission. This information is received from the powertrain control module (PCM) on the class 2 serial communication line.

Trim Value: The scan tool displays 0-255 counts. Display indicates the vehicle trim height value programmed in the RIM.

Trunk Ajar Switch: The scan tool displays On/Off. Display indicates the state of the trunk ajar switch.

Trunk Ajar Switch Active: The scan tool displays On/Off. Display indicates the state of the trunk ajar switch only when the content theft deterrent (CTD) system is armed.

Trunk Disarm Switch: The scan tool displays On/Off. Display indicates the state of the trunk disarm switch.

Trunk Release Output: The scan tool displays On/Off. Display indicates the commanded state of the trunk release output.

Trunk Release Switch: The scan tool displays On/Off. Display indicates the state of the trunk release switch.

Twilight Delay Pot: The scan tool displays 0-5 volts. Display indicates the twilight delay switch input signal in volts.

Twilight Photocell: The scan tool displays 0-5 volts. Display indicates the ambient light sensor input signal.

Vehicle Speed: The scan tool displays 0-155 mph (0-249 km/h). Display indicates the value that is used to calculate various modes of operation when the vehicle is moving.

Wiper Switch: The scan tool displays On/Off. Display indicates the status of the wiper switch.

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