GM Service Manual Online
For 1990-2009 cars only

Your vehicle may have the dual automatic climate control system. With this system you can control the heating, cooling and ventilation for your vehicle.


Object Number: 849607  Size: B2

When your vehicle is first started and the climate control system is on, or if the climate control system has been turned on, the display will show the driver's temperature setting for five seconds. Then it will show the outside temperature.

Outside Air Temperature Display

A new outside temperature reading will be displayed if the vehicle has been off for more than three hours. If the vehicle has been off for less than three hours, the old temperature reading may be displayed because underhood heat is affecting the true outside temperature.

Since underhood heat can also affect the outside temperature while the engine is running, it may take several minutes of driving before the display updates to the actual outside temperature.

(Off): Press this button to turn off the entire climate control system. Outside air will still enter the vehicle, and will be directed to the floor. Press the AUTO button, the mode button, the fan arrows, or either temperature knob to turn the system on.

(Mode): Press this button to manually select the air delivery mode to the floor, instrument panel, or windshield outlets. The system will stay in the selected mode until the mode button is pressed again or the AUTO button is pressed.

Driver's Side Temperature Knob: Turn this knob clockwise or counterclockwise to manually raise or lower the temperature on the driver's side of the vehicle. The display will show the temperature setting decreasing or increasing and an arrow pointing toward the driver. This knob can also adjust the passenger's side temperature setting simultaneously if the two zones are linked.

Passenger's Side Temperature Knob: Turn this knob clockwise or counterclockwise to manually raise or lower the temperature on the passenger's side of the vehicle. The display will show the temperature setting decreasing or increasing and an arrow pointing toward the passenger. The passenger's temperature setting can be set to match and link to the driver's temperature setting by pressing and holding the AUTO button for three seconds. Now, by adjusting the driver's side temperature setting, the passenger's side temperature setting will follow and both arrows will appear on the display. The passenger's side temperature setting also resets and relinks to the driver's side temperature setting if the vehicle has been off for more than three hours.

Automatic Operation

AUTO (Automatic): When automatic operation is active, the system will control the inside temperature, the air delivery mode, and the fan speed.

Use the steps below to place the entire system in automatic mode:

  1. Press the AUTO button.
  2. When AUTO is selected, the air conditioning operation and air inlet mode will be automatically controlled. The air conditioning compressor will run when the outside temperature is over approximately 40°F (4°C). The air inlet will normally be set to outside air. If it's hot outside, the air inlet will automatically switch to recirculate inside air to help quickly cool down your vehicle.

  3. Set the driver's and passenger's temperature.
  4. To find your comfort setting, start with a 72°F (22°C) temperature setting and allow about 20 minutes for the system to regulate. Turn the driver's or passenger's side temperature knob to adjust the temperature setting as necessary. If you choose the temperature setting of 60°F (15°C), the system will remain at the maximum cooling setting. If you choose the temperature setting of 90°F (32°C), the system will remain at the maximum heat setting. Choosing either maximum setting may not cause the vehicle to heat or cool any faster.

Manual Operation

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

(Fan): This button allows you to manually adjust the fan speed. Press the up arrow to increase fan speed and the down arrow to decrease fan speed. The display will change to show you the selected fan speed and the driver's side temperature setting for five seconds.

(Mode): Press this button to manually change the direction of the airflow in your vehicle. Keep pressing the button until the desired mode appears on the display. The display will change to show you the selected air delivery mode and the driver's temperature setting for five seconds.

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

(Bi-Level): This mode directs approximately half of the air to the instrument panel outlets, then directs the remaining air to the floor outlets. A little air is directed toward the windshield and the side window outlets. Cooler air is directed to the upper outlets and warmer air to the floor outlets.

(Floor): This mode directs most of the air to the floor outlets. Some air also comes out of the defroster and side window outlets. The recirculation button cannot be selected in floor mode.

(Recirculation): Press this button to turn recirculation mode on or off. When this button is pressed, an indicator light in the button will also come on to let you know that it is activated. Recirculation mode is used to recirculate the air inside of your vehicle. Use this mode to help prevent outside odors and/or dust from entering your vehicle or to help cool the air inside of your vehicle more quickly. Recirculation mode can be used with vent and bi-level modes, but it cannot be used with floor, defog or defrost modes. See "Defogging and Defrosting" later in this section. You may also notice that the air conditioning compressor will run while in recirculation mode. This is normal and will help to prevent fogging. If the weather is cold and damp, the system may cause the windows to fog while using recirculation mode. If the windows do start to fog, select defog or defrost mode. Recirculation mode, if selected, will be cleared when the engine is turned off.

A/C (Air Conditioning): Press this button to manually turn the air conditioning system on or off. When the system is on, the system will automatically begin to cool and dehumidify the air inside of your vehicle. The air conditioning symbol will appear on the display when the air conditioning is on and will turn off when the air conditioning is off. If you select turn the air conditioning off while in front defrost or defog mode, the air conditioning symbol will turn off, however, the A/C compressor will remain on to help de-humidify the air inside the vehicle. If one of the other modes is selected the compressor will then turn the A/C off until it is selected again or the AUTO button is pressed. You may notice a slight change in engine performance when the air conditioning compressor shuts off and turns on again. This is normal.

Defogging and Defrosting

Fog on the inside of 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. You can use either defog or front defrost to clear fog or frost from your windshield.

(Defog): Use this setting to clear the windows of fog or moisture. This setting will deliver air to the floor and windshield outlets.

(Defrost): Press the front defrost button to clear the windshield and side windows of frost or fog quickly. The system will automatically control the fan speed if you select defrost from AUTO mode. If the outside temperature is 40°F (4°C) or warmer, your air conditioning compressor will automatically run to help dehumidify the air and dry the windshield. Do not drive the vehicle until all the windows are clear.

Rear Window Defogger

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

(Rear): 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.

The rear window defogger will turn off approximately 10  minutes after the button is pressed. If you need additional warming time, press the button again.

If equipped, your heated mirrors will also come on when you press this button.

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.