1997 Buick Regal Owner's Manual - Page 166

Heating On cold days, use HTR with the temperature knob all the way in the red area. The system will bring in outside air, heat it and send it to the floor ducts. If your vehicle has an engine coolantheater, you can use it to help your system provide warm air faster when it's cold outside (0°F (-18°C) or lower). An engine coolant heater warms the coolant your engine and heating system use to provide heat. See "EngineCoolant Heater" in the Index. Ventilation System Adjust the direction of airflow by moving the louvered vents. Defogging and Defrosting Your system has two settings for clearing the front and side windows. To defrost the windows quickly, use FRONT and full hot (90°F (32°C)). Driver sets temperature and selects high fan speed. To warm passengers while keeping the windows clear, push the AIR FLOW button until WINDSHTELDFLOOR appears in the display. Select fan speed for comfort and windshield clearing performance. Your vehicle's flow-through ventilation system supplies outside air into the vehicle when it is moving. Outside air will also enter the vehicle when the air conditioning fan is running. If the airflow seems very low when the fan knob is turned to the highest setting regardless of the mode setting, your passenger compartment airfilter may need to be replaced. See "Maintenance Schedule"in the Index. 3-10