For 1990-2009 cars

The air conditioning (A/C) switch controls the operation of the A/C system. The A/C switch is mounted on the heater control unit. In all of the modes, the A/C switch must be in the ON position in order to engage the compressor. When the A/C switch is pressed, the switch signals the A/C compressor control module that A/C system operation has been requested.

The position of the temperature control lever on the heater control unit controls the A/C output temperature. A cable connects the lever to the air flow door in the heater case. The air flow door controls the air flow through the heater core as the temperature control lever is rotated through the full movement.

### Temperature Lever

The temperature lever controls the amount of air flow to the heater core and regulates the temperature of the air that enters the vehicle.

When you move the temperature lever completely to the left or full COLD (blue) position, the air mix door closes blocking the flow of air to the heater core. When you move the lever completely to the right or full HOT (red) position, the air mix door opens fully allowing the air to flow through the heater core.

Moving the temperature lever in between these 2 extremes allows the operator to adjust the passenger compartment temperature to the most comfortable level.

### Mode Lever

The mode lever allows the driver to route air into the passenger compartment through different outlets. The mode lever operates as follows:

Ventilation: In this position, air is discharged from the upper air outlet. The blower speed control lever controls the air quantity. Vehicle speed affects the air quantity when the fresh/recirc lever is set in FRESH. The faster the vehicle moves, the more air is delivered inside the passenger compartment. Some air is delivered when the blower speed is in the OFF position.
Bi-Level: In this position, airflow is divided between the upper air outlets and the floor air outlets. Warmer air is delivered to the floor outlets than is delivered to the upper air outlets.
Heat: In this position, air is directed toward the floor outlet along with a small amount to the windshield.
Heat/Defroster: In this position, a portion of the heated air is directed to the windshield while the remaining air is delivered to the floor and the side window outlets.
Defrost: In this position, most of the air is directed to the windshield. A small amount of air delivered to the side windows and to the floor.

### Blower Speed Lever

The blower speed lever regulates the amount of air delivered into the passenger compartment. The blower speed lever has 5 positions: OFF and speeds 1-4. The blower motor is housed in the blower case and located behind the right side of the IP.

### Fresh/Recirc Lever

The fresh/recirc lever determines whether fresh outside air or recirculated passenger compartment air enters the vehicle's heater and ventilation system.

Moving the fresh/recirc lever to the recirculate position provides the quickest air delivery by closing the blower mode door. In this position, outside air is not delivered to the passenger compartment. Because the vehicle has a full-time outside air system, a small amount of outside air constantly enters the passenger compartment. Recirculate mode helps in heating the passenger compartment quickly. However, during the normal heater operation use the fresh mode in order to prevent window fogging.