defroster air flow on 2002 Chevrolet Avalanche 2500

i asked a question earlier about this being a possible problem with the fan speed switch. in the defroster or vent mode very little air flow on high. when turned to bi-level and recirrculating you hear and can feel more air flow. since this problem started the was times it would kick up and run a few minutes and go back down. after doing research and trouble shooting could this be an air flow problem with the door actuator. if so how easy is it to rememdy the problem??

by in Anchorage, AK on December 18, 2009
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3 answers
ANSWER by , May 12, 2010
i finally found out the problem to my defrroster air flow problem. being an old back yard mechanic, i was not knowledgeable on some of the items in the newer model vehicles. the problem was the cabin air filter. it had not been changed in the 8 years i have owned the truck. it was definatly clogged. it was an easy r&r once i knew about it.
ANSWER by , December 19, 2009
There's a good chance one of the doors are binding, or the control system is malfunctioning. You might find a free repair manual here: or go to or and get an online repair manual subscription to learn more about how to address this issue.
ANSWER by , September 20, 2010
the vent are all working but there is no air coming out of the defroster on the windshield