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.
Heating Ventilation And Air Conditioning Module
DESCRIPTION
| 1 - HVAC Module |
The Heating, Ventilation and Air Conditioning (HVAC) module is a microcontroller designed to operate the heating and A/C system, using the Controller Area Network - Interior High Speed (CAN-IHS) data bus. The HVAC module has a plastic housing with two electrical connector receptacles, two mounting screw bosses and two locating tabs. The 36-pin electrical connector contains the power circuits, CAN-IHS circuits that connect the HVAC module to the other modules in the vehicle as well as circuits for the controls on the HVAC housing and the A/C heater control. The 8-pin connector contains the in-car temperature sensor signal circuits.
The HVAC module receives broadcast messages from the Body Control Module (BCM) containing the ambient temperature sensor data and the Humidity Rain Light Sensor Module (HRLSM) data.
The HVAC module is mounted to the lower side of the HVAC housing, between the HVAC distribution housing and the blower motor.
The HVAC module in this vehicle controls the Local Interface Network (LIN) communication for the Rear Climate Seat Switch Module, Comfort Seat Module Front Left, Comfort Seat Module Front Right, Comfort Seat Module Rear Left, Comfort Seat Module Rear Right and Comfort Steering Wheel Surface Module. For information about these heated/cooled systems, refer to HEATED AND COOLED ACCESSORIES, DESCRIPTION AND OPERATION .
OPERATION
The HVAC module utilizes integrated circuitry and information carried over the CAN-IHS data bus to monitor many sensors and switch inputs throughout the vehicle. In response to those inputs, the internal circuitry and programming of the HVAC module allows it to control electronic functions and features of the heating and A/C system.
For additional information about the HVAC module and its inputs and outputs. Refer to FRONT HVAC CONTROLS, DESCRIPTION AND OPERATION .
The HVAC module is diagnosed using a diagnostic scan tool. Prior to replacing an HVAC module, run the calibration procedure to verify that the concern is not an air door calibration issue. Refer to HVAC VERIFICATION TEST .
The HVAC module cannot be adjusted or repaired and must be replaced if inoperative or damaged.
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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.