1999 Buick Riviera Owner's Manual - Page 148

yellowblue Defogging and Defrosting Use the FRONT button to quickly remove fog, frost or ice from the windshield in extremely humid or cold conditions. Select the FRONT button to defrost the windshield. By choosing this button, the airflow will be directed at the windshield. Adjust your comfort level by pressing the TEMP up or down arrow. The fan speed will be controlled by the system. You can change the fan speed by pressing the top of the FAN button to increase speed, and the bottom of the button to decrease speed. At speeds above 30 mph (48 km/h), the rear defogger will stay on until you press the REAR defogger button again. At speeds below 30 mph (48 km/h), the rear window defogger will turn off automatically after about 10 minutes of use. If you press it again, the defogger will operate for about five minutes only. You can also turn the defogger off by turning off the ignition. NOTICE: Scraping the inside of your rear window could cut and damage the heater. Your warranty would not cover this damage. Don't put decals there because you might have to scrape them off. Rear Window Defogger The lines you see on the rear window warm the glass. Press the button to start warming your window. An indicator light in the button will glow while the rear window defogger is operating. 3-6