2004 Buick Regal Owner's Manual - Page 117

On cool, but sunny days, the sun may warm your upper body, but your lower body may not be warm enough. Select BI-LEV and set the temperature levers to a comfortable setting. The system will bring in outside air and direct it to your upper body, while sending slightly warmed air to your lower body. Push the A/C button for cooling. To defrost the window quickly, turn the mode knob to the defrost setting and turn the driver's and passenger's temperature levers all the way to the red area. To warm passengers while keeping the windows clear, use BLEND. Do not drive the vehicle until all the windows are clear. Defogging and Defrosting Fog on the inside of the windows is a result of high humidity causing moisture to form and condense on the cool window glass. This can be minimized if the climate control system is used properly. There are two modes to clear fog or frost from the windshield and side windows. Use the blend mode to clear the windows of fog or moisture and warm the passengers. Use the defrost mode to remove frost or fog from the windshield more quickly. For best results, clear all snow and ice from the windshield before defrosting. Rear Window Defogger