Chevrolet Suburban 2007 Owner's Manual page 231

There is also an exterior temperature sensor
located behind the front grille. This sensor reads
the outside air temperature and helps maintain the
temperature inside the vehicle. Any cover on
the front of the vehicle could cause a false reading
in the displayed temperature.
The climate control system uses the information
from these sensors to maintain your comfort
setting by adjusting the outlet temperature, fan
speed, and the air delivery mode. The system may
also supply cooler air to the side of the vehicle
facing the sun. The recirculation mode will also be
used as needed to maintain cool outlet
temperatures.
Defogging and Defrosting
Fog on the inside of the windows is a result of
high humidity (moisture) condensing on the
cool window glass. This can be minimized if the
climate control system is used properly. There are
two modes to clear fog or frost from your
windshield.
Use the mode up and down arrows to select the
defog or defrost modes.
-
(Defog): The defog mode is used to clear the
windows of fog or moisture and warm the
passengers. This mode directs air to the
windshield, floor outlets, and side window vents.
When you select this mode, the system turns
off recirculation and runs the air conditioning
compressor unless the outside temperature is
close to freezing. The recirculation mode cannot
be selected while in the defog mode. Do not drive
the vehicle until all the windows are clear.
0
(Defrost): Press this button to remove fog or
frost from the windshield more quickly. This
mode directs a portion of the air to the windshield
and side window vents and some to the floor
vents. In this mode, the system will automatically
force outside air into your vehicle. The
recirculation mode cannot be selected while in the
defrost mode. The air conditioning compressor
will run automatically in this setting, unless
the outside temperature is close to freezing. Do
not drive the vehicle until all the windows are clear.
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