Air Duct: Description and Operation

Air utilized by the HVAC system is drawn into the heater and evaporator module through the air inlet assembly at the base of the windshield and routed through the blower. The blower forces the air through the air filters and then through the evaporator core where it is dehumidified and cooled. The air is then heated as required by passing through or around the heater core. Now conditioned, the air is directed by air valves in the heater and evaporator module to the outlets in the instrument panel, to the heater outlets at the floor, front and rear, or to the defroster outlets, depending upon the mode selected by the driver.

The valves inside of the heater and evaporator module are controlled by 4 electric actuators. The 4 actuators that are used to control the airflow in and out of the heater and evaporator module are as follows:
^ Driver air temperature mix door actuator
^ Passenger air temperature mix door actuator
^ Rear air temperature mix door actuator
^ Mode door actuators
^ Air inlet actuator

Air Inlet Valve
The air inlet assembly provides outside or inside air to the blower depending on the mode selected by the operator The amount of inlet air is varied by an actuator that is controlled by the Instrument Panel Integration Module (IPM).

A/C Outlets
The A/C outlets are located in the instrument panel for the driver and the passenger and the center seat or center console for the passengers in the rear of the vehicle. Adjusting the air deflector control knob on the front of each outlet independently controls the airflow coming from each outlet.

Mode Air Valve
Once conditioned to the correct temperature, the air enters the air distribution chamber. The two valves in the heater and evaporator module, and one valve in the rear distribution module, are positioned by the Instrument Panel Integration Module (IPM) and the rear HVAC control, through the use of the mode actuator. By varying the position of the mode valve, the air distribution chamber is able to direct airflow to the floor, windshield, instrument panel outlets and the rear outlets.

Heater Outlet
The heater outlets are located at the base of the heater and evaporator module near the center of the vehicle. The outlet distributes air to the left and right sides of the vehicle through a duct that is attached to the evaporator module. The heater and evaporator module also distributes to the rear passengers. The rear air is distributed by outlets located under the front seats and by an outlet in the center seat or the center console.

Windshield Defroster Nozzle
The windshield defroster air duct is located on the top of the heater and evaporator module and directs airflow to the base of the windshield and to the side windows. The side window defogger outlets are located in each front doors.