I have a 93 k1500. When I start and shut off the truck there is a ticking behind the fan that lasts about 10 scs. I pulled the fan out and it's ok, nothing in it. Behind the fan I guess it is the control for the flap near the floor board I think is what is ticking. I can feel the flap and can feel it trying to move, but it doesn't. Could the control be stripped or could the flap be stuck. I can push the flap up a little but not alot. Any help thanks.