2007 Cadillac STS Owner's Manual - Page 233

Recirculation is not available in the defrost mode and shuts off when defog mode is selected. Both of these features are designed to limit fogging in the vehicle. If recirculation is selected during defog mode, it automatically turns off after 10 minutes to limit problems with fogging. In some conditions, using recirculation for long periods of time can cause the air inside the vehicle to become too dry or stuffy. To prevent this from happening, after the air in the vehicle has cooled, select AUTO to return to automatic climate control operation or push the recirculation button again to select outside air. Press this button a second time to select outside air. exhaust fumes from older, poorly running, or diesel-equipped vehicles that are driving near you. This sensor, when active, monitors the air quality in front of your vehicle and switches to air recirculation when poor quality air is detected outside your vehicle. Press the AUTO button on the climate control to activate the air quality sensor. The word AUTO comes on the center of the climate control display. While the air quality sensor senses poor quality air, the recirculation graphic displays. Under some conditions, the air quality sensor system does not operate. In cold weather, the system might not be active (even if AUTO is displayed) because of concerns of fogging your windows, which may occur by activating recirculation mode. Also, the air quality sensor system does not remain in recirculation mode for extended periods of time that could cause stuffy or very dry conditions in the vehicle. Following a poorly running vehicle for an extended period of time may not keep recirculation active indefinitely. : (Outside Air): This mode forces the system to pull air from outside the vehicle. It can be used to bring fresh air into the vehicle. Air Quality Sensor: Your vehicle could have an air quality sensor to help limit the climate control system from pulling in some harmful 233