Cadillac 2004 Seville - Manual (Page 143)

Sensors The solar sensor on your vehicle monitors the solar
radiation inside your vehicle, then uses the information
to maintain the selected temperature by initiating
needed adjustments to the temperature, the fan speed
and the air delivery system. The system may also
supply cooler air to the side of the vehicle facing the
sun. The recirculation mode will also be activated,
as necessary. Do not cover the solar sensor located in
the middle of the instrument panel, near the windshield
or the system will not work properly.
There is also an outside temperature sensor located
under the front bumper and an inside temperature
sensor located to the left of the ignition switch. These
sensors read the outside and inside air temperature and
help to maintain the selected temperature inside the
vehicle. If you cover these sensors, it could cause
a false reading in the temperature.
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