Chevrolet 2003 Avalanche Owner's Manual page 184

Heating
On cold days when using manual operation of the
automatic system, choose floor mode to deliver air to
the floor outlets. To warm or cool the air delivered, turn
the temperature knob to the desired setting.
If you want to use the automatic mode, press AUTO and
adjust the temperature by turning the temperature knob.
The heater works best if you keep the windows closed
while using it.
Defogging and Defrosting
You can use either defog or front defrost to clear fog or
frost from your windshield. Use the defog mode to
clear the windows of fog or moisture. Use the front
defrost button to defrost the front windshield.
(Defog): Use this setting to clear the windows of fog
or moisture. Press the mode button to select this
setting. This setting will deliver air to the floor and
windshield outlets.
@
(Front Defrost): Press the front defrost button to
defrost the windshield. The system will automatically
control the fan speed if you select defrost from AUTO
mode. If the outside temperature is
40°F
(4°C) or
warmer, your air conditioning compressor will
automatically run to help dehumidify the air and dry the
windshield.
Rear Window Defogger
If your vehicle has this feature the lines you see on the
rear window warm the glass. The rear window
defogger uses a warming grid to remove fog from the
rear window.
(Rear): Press this button to turn the rear window
defogger on or off. An indicator light in the button
will come on to let you know that the rear window
defogger is activated.
The rear window defogger will turn off approximately
10 minutes after the button is pressed. If you need
additional warming time, press the button again.
If you vehicle is equipped with heated mirrors this button
will activate them.
Notice: Don't use a razor blade or something else
sharp on the inside of the rear window. If you
do, you could cut or damage the defogger and the
repairs would not be covered by your warranty.
Do not attach a temporary vehicle license, tape, a
decal or anything similar to the defogger grid.
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