GM Service Manual Online
For 1990-2009 cars only

Your vehicle may be equipped with a dual or single climate control system. With this system you can control the heating, cooling, defrost, defog and ventilation for your vehicle.

Dual Zone with Optional Heated Seat Controls


Object Number: 1542656  Size: B2

Single Zone


Object Number: 1585484  Size: B2

Manual Operation

Turn the right knob clockwise or counterclockwise to direct the airflow inside of your vehicle.

To change the current mode, select one of the following:

(Vent):  This mode directs air to the instrument panel outlets.

(Bi-Level):  This mode allows for approximately half of the air to the instrument panel outlets and to the floor outlets.

(Floor): This mode directs most of the air to the floor outlets, with some of the air directed to the windshield and side window outlets. In this mode, the system will automatically select Outside Air.

The right knob can also be used to select defog or defrost mode. For more information, see "Defogging and Defrosting" later in this section.

By positioning the right knob between two modes, a combination of those two modes is selected.

It should be noted, that the air conditioning compressor will be engaged unless the outside temperature is 40°F (4°C) or below. Recirculation cannot be selected when in Floor Mode.

(Fan):  Turn the left knob clockwise or counterclockwise to increase or decrease the fan speed. If the airflow seems low when the fan is at the highest setting, the passenger compartment air filter, if equipped, may need to be replaced. For more information, see Passenger Compartment Air Filter and Scheduled Maintenance .

(Outside Air):  Press this button to turn the outside air mode on. When this mode is on, outside air will circulate throughout your vehicle. When the button is pressed, an indicator light in the button will come on to let you know that it is activated. The outside air mode can be used with all modes, but it cannot be used with the recirculation mode.

(Recirculation): Press this button to turn the recirculation mode on. When the button is pressed, an indicator light will come on. This mode keeps outside air from entering the vehicle. It can be used to prevent outside air and odors from entering your vehicle. Recirculation may also help heat or cool the air inside your vehicle more quickly once the temperature inside the vehicle is equal to or better than the outside temperature. The recirculation mode cannot be used with outside air, floor, defrost, or defogging modes.

Temperature Control:  Rotate the thumbwheels up or down to increase or decrease the temperature on the driver's side or the passenger side of the vehicle for the dual zone system. Turn the center knob clockwise or counterclockwise to increase or decrease the temperature for the single zone system.

(Air Conditioning):  Press this button to turn the air conditioning system on or off. When A/C is pressed, an indicator light will come on to let you know that the air conditioning has been activated.

On hot days, open the windows to let hot inside air escape; then close them. This helps to reduce the time it takes for your vehicle to cool down. It also helps the system to operate more efficiently.

For quick cool down on hot days, do the following:

  1. Select the vent mode.
  2. Select the outside air.
  3. Select A/C.
  4. Select the coolest temperature for both zones.
  5. Select the highest fan speeds.
  6. Once the vehicle's interior temperature is below the outside temperature, select recirculation mode for enhanced cooling.

Using these settings together for long periods of time may cause the air inside of your vehicle to become too dry. To prevent this from happening, after the air inside of your vehicle has cooled, turn the recirculation mode off.

The air conditioning system removes moisture from the air, so you may sometimes notice a small amount of water dripping underneath your vehicle while idling or after turning off the engine. This is normal.

Defogging and Defrosting

Fog on the inside of the windows is a result of high humidity (moisture) condensing on the cool window glass. This can be minimized if the climate control system is used properly. There are two modes to clear fog or frost from your windshield. Use the defog mode to clear the windows of fog or moisture and warm the passengers. Use the defrost mode to remove fog or frost from the windshield more quickly.

Turn the right knob clockwise to select the defog or defrost mode. Do not drive the vehicle until all the windows are clear.

(Defog):  This mode directs air equally to the windshield and the floor outlets. When you select this mode, the system turns off recirculation and runs the air conditioning compressor unless the outside temperature is below 40°F (4°C). The recirculation mode cannot be selected while in the defog mode.

(Defrost): This mode directs a portion of the air to the windshield and side window vents and some to the floor vents. In this mode, the system will automatically force outside air into your vehicle. The recirculation mode cannot be selected while in the defog mode. The air conditioning compressor will run automatically in this setting, unless the outside temperature is below 40°F (4°C).

Rear Window Defogger

The rear window defogger uses a warming grid to remove fog from the rear window.

The rear window defogger will turn off automatically after it has been activated. The duration the rear window defogger is on will be longer if the vehicle is being driven. The defogger can also be turned off by pressing the button again or by turning off the engine.

If your vehicle has heated outside rearview mirrors, the mirrors will heat to help clear fog or frost from the surface of the mirror when the rear window defog button is pressed.

Notice: Do not use anything sharp on the inside of the rear window. If you do, you could cut or damage the warming grid, and the repairs would not be covered by the vehicle warranty. Do not attach a temporary vehicle license, tape, a decal or anything similar to the defogger grid.