GMC 2012 Sierra Series Owner's Manual page 283

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
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.
I n f o r ma t i o n P r o v i d e d b y :
Climate Controls 8-11