2004 Chevrolet Express Van Owner's Manual - Page 141

1(Defrost): This setting operates the defroster. Most of the air comes out near the windshield, with some going to the floor outlets and front side windows. The air conditioning compressor may operate in this setting to dehumidify the air. The blend setting is useful for cold weather with a large number of passengers or very humid conditions to help keep the windshield clear. Use defrost to remove fog or ice from the windshield quickly in extremely cold conditions. The temperature knob should be in the red area and the fan control toward high. Do not drive the vehicle until all the windows are clear. Rear Window Defogger < R. DEF (Rear Defrost): Press this button to turn the rear window defogger on or off. Be sure to clear as much snow from the window as possible. The rear window defogger uses a warming grid to remove fog or frost from the rear window and will only work when the ignition is RUN. The rear window defogger will turn off several minutes after the button is pressed. If turned on again, the defogger will run for several more minutes before turning off. The defogger can also be turned off by pressing the button again or by turning off the engine. Notice: Using a razor blade or sharp object to clear the inside rear window may damage the rear window defogger. Repairs would not be covered by your warranty. Do not clear the inside of the rear window with sharp objects. 3-21