2008 Cadillac STS Owner's Manual - Page 206

Sensors 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. Defogging and Defrosting Fog on the inside of 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 from the windshield. Use the defog mode to clear the windows of fog or moisture and warm the passengers. Use the defrost mode to remove fog or frost from the windshield more quickly. yN z (Mode): on the display. There is a solar sensor located on the instrument panel, near the windshield. There is also an interior temperature sensor located next to the steering wheel on the instrument panel. These sensors monitor the solar radiation and the air inside the vehicle, then use the information to adjust the temperature, the fan speed and the air delivery system, in order to maintain the selected temperature. Press this button until defog appears - (Defog): This mode directs the air between the windshield and floor outlets with some air supplied to the outboard panel outlets and side window defogging outlets. When this mode is selected, the system turns off recirculation and runs the air-conditioning compressor unless the outside temperature is at or below freezing. The recirculation mode is cancelled when the system enters the defog mode. If recirculation is selected while in the defog mode, it is cancelled after 10 minutes. 3-52