Defogging And Defrosting - GMC Yukon Denali 2003 Owner's Manual

When air conditioning is selected or in AUTO mode, the
system will run the air conditioning automatically to
cool and dehumidify the air entering the vehicle. If you
select A/C off while in front defrost, defog or
recirculation, the A/C snowflake symbol will turn off, but
the A/C compressor will still run to help prevent
fogging.
On hot days, open the windows long enough to let hot
inside air escape. This reduces the time it takes for
your vehicle to cool down. Then keep your windows
closed for the air conditioner to work its best.
On cool, but sunny days while using manual operation
of the automatic system, use bi-level to deliver warm
air to the floor and cooler air to the instrument
panel outlets. To warm or cool the air delivered, turn the
temperature knob to the desired setting.
In AUTO mode the system will cool and dehumidify the
air inside the vehicle. Also while in AUTO mode, the
system will maximize its performance by using
recirculation as necessary.
^
(Air Conditioning Off): On some vehicles, when
you turn the air conditioning off, this symbol will appear
on the display. If your vehicle does not have this
symbol, the snowflake symbol will turn off to let you
know the air conditioning is off.
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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.
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(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.
0
(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.