Air Delivery

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Front Control

The HVAC control module controls the distribution of air by the use of recirculation and mode actuators. The modes that may be selected are:

Defrost
Defog
Panel
BI-Level
Floor

The mode actuator is connected to the mode door by a cam type linkage system. Depending on the position of the door, air is directed through the HVAC module and distributed through various ducts leading to the outlets in the dash. If a fault is detected within the mode door travel, the HVAC control module will drive the actuator to defrost, which is a default position for the mode door actuator. Turning the mode door position to either defrost or defog positions, the HVAC control module will move the recirculation actuator to outside air reducing window fogging. When defrost/defog is selected, the A/C compressor is activated. The A/C compressor clutch will engage when ambient temperatures are above 3°C (38°F). A/C is available in all modes. Recirculation is only available in Panel and Bi-Level modes. The rear window defogger does not affect the HVAC system.

Auxiliary Control

The auxiliary HVAC system provides ventilation for the rear seat occupants. The rear seat occupants will exercise control of the auxiliary air delivery modes, air speed and the air temperature setting. The HVAC control module will have the ability to override the auxiliary HVAC control module by placing it in any position other than auxiliary.

The auxiliary mode switch in the HVAC control module allows the driver to direct the air flow in the rear of the vehicle between the floor, headliner, or a blend between the 2 options. Power is provided to both front and auxiliary HVAC control modules from I/P fuse block on the ignition 3 voltage circuit.