GMC Sierra Owners Manual
Air VentsClimate Controls / 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.
• 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 before adding equipment to the outside of the vehicle.