1999 GMC Sonoma Owner's Manual - Page 129

yellowblue Defogging and Defrosting On cool, humid days, use BLEND to keep the windshield and side windows clear. Use DEFROST to remove fog or ice from the windshield quickly in extreme humid or cold conditions. Turn the temperature knob clockwise and turn the fan control toward high. If you have the heated outside mirror feature, you can use it to defog or defrost your outside mirrors. For more information, see "Heated Outside Mirrors" in the Index. Ventilation System For mild outside temperatures when little heating or cooling is needed, use VENT to direct outside air through your vehicle. Airflow is through the instrument panel outlets. Your vehicle's ventilation system supplies outside air to the inside of your vehicle when it is moving. When the vehicle is not moving, you can get outside air to flow through by selecting any mode and any fan speed. You will find air outlets in the center and on the sides of your instrument panel. You can direct the airflow side-to-side by moving the thumbwheel located in the center of the vent. The vent can be tilted up and down also. To control the amount of airflow through the outlets, move the thumbwheel below the vent. 3-5