GM Service Manual Online
For 1990-2009 cars only

With this system you can control the heating, cooling, defrost, defog and ventilation for your vehicle.


Object Number: 1253732  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 a 50/50 split of 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 information on defogging and defrosting, 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.

Selecting the Fan Speed

(Fan): Turn the left knob clockwise or counterclockwise to increase or decrease the fan speed. Turn the knob to OFF to turn off the fan. The fan must be turned on for the air conditioning compressor to operate.

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 .

Selecting Outside Air or Recirculation

The outside air mode is used to bring outside air into your vehicle; also use this mode to remove excess moisture from the inside of the windows. The recirculation mode is used to recirculate the air inside of your vehicle; also use this mode to help prevent outside odors and/or dust from entering your vehicle or to help heat or cool the air inside of your vehicle quickly.

(Outside Air): Press this button to turn the outside air mode on. When this button is pressed, an indicator light in the button will come on to let you know that it is activated. During daylight hours, you may have to adjust the instrument panel brightness control to the highest setting in order to see the indicator light. See Interior Lamps for more information. When this mode is on, outside air will circulate throughout your vehicle.

(Recirculation): Press this button to turn the recirculation mode on. When this mode is on, inside air and a small percentage of outside air will recirculate throughout your vehicle. This selection will reduce the entry of outside air and odors from entering your vehicle, it may also help heat or cool your vehicle more quickly. When this button is pressed, an indicator light in the button will also come on to let you know that it is activated. During daylight hours, you may have to adjust the instrument panel brightness control to the highest setting in order to see the indicator light. See Interior Lamps for more information. The recirculation mode can be used with vent and bi-level modes, but it cannot be used with floor, defog, defrost or outside air modes. This system will default back to the outside air setting, so you will have to re-select this setting every time that you start the vehicle. If the weather is cold and damp, the system may cause the windows to fog while using the recirculation mode. If the windows do start to fog, do the following:

  1. Select the defog or defrost mode.
  2. Select the temperature.
  3. Select the highest fan speed.
  4. Operate the system in the outside air mode, to help prevent a recurrence.

Heating

Adjust the air temperature by using the following levers:

D (Driver): Slide this lever up or down to raise or lower the temperature on the driver's side of the vehicle.

P (Passenger): Slide this lever up or down to raise or lower the temperature on the passenger's side of the vehicle.

To warm your vehicle on cold days, do the following:

  1. Select the floor mode.
  2. Select the warmest temperature.
  3. Select the fan speed.
  4. Select outside air mode, after the air has warmed, to prevent it from becoming too stale.

When it's cold outside 0°F (-18°C) or lower, use the engine coolant heater, if equipped, to provide warmer air faster to your vehicle. An engine coolant heater warms the coolant that the engine uses to provide heat to warm the inside of your vehicle. For more information, see Engine Coolant Heater .

Cooling

On hot days, open the windows to let hot 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.

(Air Conditioning): Press this button to turn the air-conditioning system on or off. When the system is on, an indicator light will come on and the system will begin to cool and dehumidify the air inside of your vehicle. During daylight hours, you may have to adjust the instrument panel brightness control to the highest setting in order to see the indicator light. See Interior Lamps for more information. You may notice a slight change in engine performance when the air-conditioning compressor shuts off and turns on again. This is normal. The system is designed to make adjustments to help with fuel economy while still maintaining the selected temperature. The Air Conditioning System removes moisture from the air, so you may notice a small amount of water dripping underneath your vehicle when idling or after turning off the engine.

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

  1. Select the vent mode.
  2. Select A/C.
  3. Select the recirculation mode.
  4. Select the coolest temperature for both zones.
  5. Select the highest fan speeds.

Using these settings together for long periods of time may cause the air inside of your vehicle to become too dry. To prevent this, after the air inside of your vehicle has cooled, switch to Outside Air.

On cool, but sunny days, the sun may warm the upper part of your body, but the lower part may not be warm enough. To remedy this, do the following:

  1. Select the bi-level mode.
  2. Select A/C.
  3. Select the temperature.
  4. Select the fan speed.

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 your 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 choose from to clear fog or frost from your windshield. Use the defog mode to clear fog or moisture from the windows and warm the passengers. Use the defrost mode to quickly remove fog or frost from the windshield.

Turn the right knob clockwise or counterclockwise to select one of the following modes:

(Defog): This mode directs half of the air to the windshield and side window vents and half 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). Do not drive the vehicle until all the windows are clear.

(Defrost): This mode directs most of the air to the windshield and the side window vents, with only a little air directed to the floor vents. In this mode, the system will automatically force outside air into your vehicle. There is a 5 minute timer linked to this function. The recirculation mode cannot be selected while in the defrost mode. The air conditioning compressor will run automatically in this setting, unless the outside temperature is below 40°F (4°C). Do not drive the vehicle until all the windows are clear.

To circulate outside air and clear the windshield quickly and bring outside air into your vehicle, do the following:

  1. Select defrost mode.
  2. Select the temperature.
  3. Select the highest fan speed.

Rear Window Defogger

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

Press this button to turn the rear window defogger on or off. An indicator light in the button will come on to let you know that the rear window defogger is activated. During daylight hours, you may have to adjust the instrument panel brightness control to the highest setting in order to see the indicator light. See Interior Lamps for more information.

The rear window defogger will turn off approximately 20 minutes after the button is pressed. If turned on again, the defogger will run for the same amount of time. 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 Rear Window Defogger also warms the heated driver's and passenger's outside rearview mirrors to help clear them of ice, snow and condensation.

Do not drive the vehicle until all the windows are clear.

Notice: Do not use a razor blade or sharp object to clear the inside rear window. Do not adhere anything to the defogger grid lines in the rear glass. These actions may damage the rear defogger. Repairs would not be covered by your warranty.

Outlet Adjustment

The flow through ventilation system on your vehicle allows outside air to enter your vehicle when it is moving. Outside air will also enter your vehicle when the air-conditioning compressor is running and even in small amounts when the recirculation mode is activated.


Object Number: 854580  Size: A3

Use the control located below or to the side of the vent, to change the direction of the air flowing through them or to shut them off.

For mild outside temperatures when little heating or cooling is needed, do the following:

  1. Select the vent mode.
  2. Select outside air mode.
  3. Select the temperature.
  4. Select the fan speed.

Ventilation Tips

    • Clear away any ice, snow or leaves from the air inlets on the hood that may block the flow of air into your vehicle. This will help to remove fog or frost from the windows it will also improve heating.
    • Select the floor mode and set the fan at the highest speed when first starting your vehicle to help clear the air intake ducts of moisture or snow. This will also help to remove fog from the windows.
    • Keep the path under the front seats clear of objects to help circulate the air inside of your vehicle more effectively.