2001 Pontiac Montana Owner's Manual - Page 236

Your vehicle is equipped with side window defogger vents located on the top of the instrument panel. For additional side window defogging, turn the mode knob to the BI-LEVEL setting and adjust the fan to the highest speed. Aim the side vents on the instrument panel toward the side windows. For increased airflow to the side vents, close the center vents. Operating the HVAC system in the RECIRCULATION mode may cause fogging of the vehicle's windows when the weather is cold and damp. To clear the fog, switch the HVAC system to either the DEFOG or DEFROST mode and increase the fan speed. To avoid re-fogging of the windows, operate the HVAC system in the OUTSIDE AIR mode. For additional information, refer to "RECIRCULATION" earlier in this section. Rear Window Defogger Press the REAR button (the light will glow) to warm the defogger grid on the rear window and to turn on the heated outside rearview mirrors. The system will turn off automatically after about 10 minutes of use. If you turn it on again, the defogger will operate for about five minutes. You can also turn the defogger off by turning off the ignition or by pressing the button again. 3-5