Air utilized by the HVAC system is drawn into the HVAC module through the air inlet assembly at the base of the windshield. The air is drawn through the air filter and routed to the blower. The blower forces the air 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 mode door in the HVAC 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 air mix doors inside the HVAC module are controlled by electric actuators. The actuators that are used to control the airflow in and out of the HVAC module are as follows:

The air inlet assembly provides outside or inside (RECIRC) air to the blower depending on the selection by the operator. The amount of inlet air may be varied by the Instrument Panel Module (IPM) (CJ2 system) or manually selected on the HVAC control head (C67 system) or (CJ2 system).

Once conditioned to the correct temperature, the air enters the air distribution chamber. Air flow doors in the HVAC module are positioned by the mode actuator. By varying the position of the air flow doors, the air distribution chamber is able to direct airflow to the floor, windshield or instrument panel outlets. The direction of the air is varied by the mode actuator that is controlled by the following:

The A/C outlets are located in the instrument panel. Adjusting the air deflector control knob on the front of each outlet independently controls the airflow coming from each outlet.

The heater outlets are located at the base of the HVAC module in the center of the vehicle. The outlet distributes air to the left and right sides of the vehicle through a duct that is molded into the sound insulators. The heater and evaporator module also distributes air to the rear passengers for those vehicles equipped. The rear air is distributed by the rear floor duct located under the front seat or console to an outlet in the center console or armrest.

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 the front door panels.