Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 446 (VEHICLE DIAGNOSTIC INFORMATION (1 OF 2))SPECIFICATIONSHEATING, VENTILATION AND AIR CONDITIONING CONTROL MODULE SCAN TOOL INFORMATION
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Heating, Ventilation and Air Conditioning Control Module Scan Tool Information
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Heating, Ventilation and Air Conditioning Control Module Scan Tool Information
WARNING: This page is about a different car, the 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
HVAC Control Module Scan Tool Data Parameters
| Parameter | System State | Expected Value | Description |
|---|---|---|---|
| Operating Conditions: Ignition ON, HVAC OFF | |||
| A/C Request | - | No | The scan tool displays Yes or No. Yes is displayed if the air conditioner is requested. |
| Ambient Air Temp. Sensor | - | Varies | This displays °F (°C). This is the current temperature at the ambient air temperature sensor. |
| Ambient Light Sensor | - | Varies | This displays Counts. This is the current ambient light measured in counts at the ambient light sensor. |
| Blower Motor Speed | - | 0% | This displays %. This is the current blower motor speed measured in percentage. |
| Blower Motor Speed Command | - | 0% | This displays %. This is the commanded blower motor speed measured in percentage. |
| Driver Program Number | - | Varies | This displays Counts. This is the driver program number measured in counts. |
| Driver Temp. Dr. Cal. Range | - | Varies | This displays Pulses. This is the driver temperature door calibration range measured in pulses. |
| Driver Temp. Dr. Motor Command | - | Varies | This displays Counts. This is the commanded driver temperature door motor request measured in counts. |
| Driver Temp. Dr. Position | - | Varies | This displays Counts or Pulses. This is the current driver temperature door position measured in either counts or pulses. |
| Inside Air Temp. Sensor | - | Varies | This displays °F (°C). This is the current temperature at the inside air temperature sensor. |
| LED Intensity | - | Varies | This displays Counts. This is the light emitting diode (LED) intensity measured in counts. |
| Left Sunload Sensor | - | Varies | This displays Counts. This is the current sunload measured in counts at the driver sunload sensor. |
| Load Management Status | - | Off | The scan tool displays On or Off. This is the status of the load management. |
| Lower Left Duct Temp. Sensor | - | Varies | This displays Counts. This is the current temperature at the driver lower duct temperature sensor measured in counts. |
| Lower Right Duct Temp. Sensor | - | Varies | This displays Counts. This is the current temperature at the passenger lower duct temperature sensor measured in counts. |
| Mode Door Position | - | Varies | This displays Counts or Pulses. This is the current mode door position measured in either counts or pulses. |
| Mode Dr. Cal. Range | - | Varies | This displays Pulses. This is the mode door calibration range measured in pulses. |
| Mode Dr. Motor Command | - | Varies | This displays Counts. This is the commanded mode door motor request measured in counts. |
| Mode Status | - | Off | The scan tool displays Off, Auto, Heater, Bi-Level, Defog, Defrost or Mid. This is the current mode of the HVAC system. |
| Psgr. Program Number | - | Varies | This displays Counts. This is the passenger program number measured in counts. |
| Psgr. Temp. Dr. Cal. Range | - | Varies | This displays Pulses. This is the passenger temperature door calibration range measured in pulses. |
| Psgr. Temp. Dr. Motor Command | - | Varies | This displays Counts. This is the commanded passenger temperature door motor request measured in counts. |
| Psgr. Temp. Dr. Position | - | Varies | This displays Counts or Pulses. This is the current passenger temperature door position measured in either counts or pulses. |
| Recirculation Temp. Dr. Cal. Range | - | Varies | This displays Pulses. This is the recirculation temperature door calibration range measured in pulses. |
| Recirculation Temp. Dr. Motor Command | - | Varies | This displays Counts. This is the commanded recirculation temperature door motor request measured in counts. |
| Recirculation Temp. Dr. Position | - | Varies | This displays Counts or Pulses. This is the current recirculation temperature door position measured in either counts or pulses. |
| Right Sunload Sensor | - | Varies | This displays Counts. This is the current sunload measured in counts at the passenger sunload sensor. |
| Seat Temp. Status | - | Off | The scan tool displays Off, Max. Cool, Mid. Cool, Min. Cool, Max. Heat, Mid. Heat or Min. Heat. This is the current state of the driver seat temperature. |
| Upper Left Duct Temp. Sensor | - | Varies | This displays Counts. This is the current temperature at the driver upper duct temperature sensor measured in counts. |
| Upper Right Duct Temp. Sensor | - | Varies | This displays Counts. This is the current temperature at the passenger upper duct temperature sensor measured in counts. |
| Valet Switch | - | Inactive | The scan tool displays Active or Inactive. This is the state of the valet switch. |
| Vehicle Speed | - | 0 km/h (0 mph) | This displays km/h (mph). This is the current vehicle speed. |
HVAC Control Module Scan Tool Output Controls
| Output Control | Description |
|---|---|
| Afterblow Option | When afterblow is activated the scan tool displays an *. |
| Blower Motor | The scan tool displays Off or On selections. This function allows you to command the blower motor to its maximum (100%) or minimum (0%) speeds for 5 seconds. |
| Compressor Clutch | The scan tool displays the A/C compressor clutch status: Engage or Disengage. This function allows you to command the A/C compressor clutch On and Off. |
| Driver Temp. Door | The scan tool displays On or Off selections. The selection drives the actuator to its minimum (cold) or maximum (hot) positions for 20 seconds. |
| Instant OAT Update | The scan tool displays Commanded State: On or Off. This function updates the HVAC control module ambient air temperature input to the current raw value. |
| Mode Door Position | The scan tool displays On or Off selections. This function drives the actuator to its minimum (defrost) or maximum (upper) positions for 20 seconds. |
| Passenger Temp. Door | The scan tool displays On or Off selections. The selection drives the actuator to its minimum (hot) or maximum (cold) positions for 20 seconds. |
| Recalibrate All Motors | When commanded the scan tool displays the actuators counts moving from hot to cold until the re-cal is complete. |
| Recirculation Door | The scan tool displays On or Off selections. This function drives the actuator to its minimum (outside air) or maximum (recirculate) stops for 20 seconds. |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.