Cadillac 2011 STS Owner's Manual page 233

The solar sensor located on the instrument panel, near
the windshield, monitors the solar heat.
The interior temperature sensor located on the
instrument panel to the right of the steering wheel,
measures the temperature of the air inside the vehicle.
The climate control system uses the information from
these sensors to adjust the temperature, the fan speed
and the air delivery, in order to maintain the selected
temperature. The system may also supply cooler air to
the side of the vehicle facing the sun.
Do not cover the sensors or the automatic climate
control system will not work properly.
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