Howdy new guy here. I was wondering if anyone knows why my AC makes a small noise inside my cab near the passegers side under the dash? It only does it when I turn on the MAX on the AC. I think it is a valve door or some sort of flap door type thing. I had the wife turn on the AC then turn on the max while I felt around under there. I could make out something on the firewall side of the what I think it the duct work for the AC making the slapping type sound. Any ideas or does anyone have any pictures of what the AC duct system looks like?

Thanks

 

it sounds like the bearing in the blower are going out.......

 

it turned out to be the blend door actuator......
And only took me half the day to take apart the dash to get to it. and cannot get part for two to three days.