1997 Buick Century Owner's Manual - Page 154

Heating On cold days,use HTR with the temperature knob all the way in the red area. Thesystem will bring in outside air, heat it and send it tothe floor ducts. If your vehicle has an engine coolantheater, you can use it to help your system provide warm air fasterwhen 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 "Engine Coolant 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 front and the side windows. To defrost thewindows 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 WINDSHIELD/FLOOR appears in the display. Select fanspeed for comfort and windshield clearing performance. Your vehicle's flow-through ventilation system supplies outside air into vehicle when it ismoving. Outside the air will also enterthe vehicle when the airconditioning 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 air filtermay need to be replaced. See"Maintenance Schedule" in the Index. 3-10