Chevrolet Silverado 2007 Owner's Manual page 249

Sensors
The solar sensor, located in the defrost grille, in
the middle of the instrument panel, monitors
the solar radiation. Do not cover the solar sensor
or the system will not work properly.
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 on the rearview mirror.
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.
The interior temperature
sensor, located in the
headliner, measures the
temperature of the air
inside your vehicle.
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