2010 Cadillac CTS Owner's Manual - Page 238

7-6 Climate Controls Under certain conditions, the air quality sensor will not activate recirculation, such as during cold weather or with odors, like skunk. To limit odors manually, press M until the condition has passed. The air quality sensor system does not protect against carbon monoxide (CO), which you cannot see or smell. See Engine Exhaust on page 8‑25. Air Vents Use the air outlets located in the center and on the side of the instrument panel to direct the airflow. Use the thumbwheels near the air outlets to open or close off the airflow. Operation Tips . Maintenance Passenger Compartment Air Filter The passenger compartment air filter traps most of the dust and pollen from the air entering the vehicle. The filter will need to be changed periodically. See Scheduled Maintenance on page 10‑3. Using the climate control system without the passenger air filter installed could let water or other debris enter the system. This could cause a water leak or noises. Make sure a new air filter is installed after removing the old one. Clear away any ice, snow, or leaves from air inlets at the base of the windshield that could block the flow of air into the vehicle. Keep the path under the front seats clear of objects to help circulate the air inside of the vehicle more effectively. Use of non-GM approved hood deflectors can adversely affect the performance of the system. Check with your dealer/retailer before adding equipment to the outside of the vehicle. . .