GMC 2010 Sierra 1500 Crew Cab Owner's Manual page 253

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.
Warning lights and gauges can signal that something is
wrong before it becomes serious enough to cause an
expensive repair or replacement. Paying attention to the
warning lights and gauges could prevent injury.
Warning lights come on when there might be or there is
a problem with one of the vehicle's functions. Some
warning lights come on briefly when the engine is
started to indicate they are working.
Gauges can indicate when there might be or there is a
problem with one of the vehicle's functions. Often
gauges and warning lights work together to indicate a
problem with the vehicle.
When one of the warning lights comes on and stays on
while driving, or when one of the gauges shows there
could be a problem, check the section that explains
what to do. Follow this manual's advice. Waiting to do
repairs can be costly and even dangerous.
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