2002 Buick Rendezvous Owner's Manual - Page 223

Heating Turn the temperature knob clockwise (toward the red area) to warm the air. In the lower mode, outside air will be brought in and sent through the floor outlets. The heater works best if you keep your windows closed while using it. The bi-level setting is designed for use on sunny days when the air is only moderately warm or cool. On days like these, the sun may adequately warm your upper body, but your lower body may not be warm enough. For the best results, move the temperature knob to the middle position, and then adjust it for comfort. Your vehicle has a computer controlled transaxle designed to warm up the engine faster when the outside temperature is 35_F (2_C) or colder. You may notice that the transaxle will shift at a higher vehicle speed until the engine is warmed up. This is a normal condition designed to provide heat to the passenger compartment and defrost the windows more quickly. If your vehicle is equipped with an engine coolant heater and you use it during cold weather, 0_F (-18_C) or lower, your heating system will provide heat more quickly because the engine coolant is already warmed. See "Engine Coolant Heater" in the Index. Defogging and Defrosting Your system has two settings for clearing the front and side windows. To rapidly defrost the windshield, turn the temperature knob all the way clockwise (to the red area) and turn the mode knob to defrost. Adjust the fan to the highest speed. To keep the windshield clear and bring in heated air through the heater ducts, turn the mode knob to defog. When the temperature outside is above freezing, the air conditioner compressor will run in these settings to help remove moisture from the air. 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. 3-4