1998 Chevrolet Corvette Owner's Manual - Page 170

Rear Window Defogger Defogging and Defrosting To rapidly defrost the windshield, the FRONT defrost mode (electronic dual climate control system) or defrost mode (manual control system) should be used and the fan speed should be adjusted to the highest speed. With the manual control system, turn the temperature control knob all the way to the red area. To keep the windshield clear and provide heated air to the floor area of the vehicle, use the DEFOG setting. Your vehicle is equipped with side window defogger vents located near the side rearview mirrors. @ This button turnsthe rear defogger and heated outside mirrorson. The light on the button will come on when operating. The system automatically shuts off after approximately 10 minutes. If further defogging is desired, press the button again. The rear window defogger operates only when the engine is running. The rear window defogger uses a warming grid to remove fog from the rear window. Do not attach anything like a temporaryvehicle license or a decal across the defogger gridon the rear window. Ventilation System 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 fan is running. NOTICE: Don't use a razor blade or something sharp on the insideof the rear window.If you do, you could cut or damage the warming grid, and repairs wouldn't be covered by your warranty. Ventilation Tips 0 Keep the hood and front air inlet free of ice, snow or any other obstruction (such as leaves). The heater and defroster will work far better, reducing the chance of fogging the inside of the windows. 3-11