The fan has 4 settings I believe. It seems like when the fan is turned up from 1 to 4 the fan sounds like it is running faster but I don't believe any more air is coming out of the vents. Also noticed that the A/C doesn't get nearly as cold as it used to. Also when the fan is turned on all the way 4 out of 4, top speed there is a vibration sound buzzing loudly that seems to be coming from the firewall. It almost sounds like the engine idle is speeding up although its not. Any ideas?

Just had the same thing about two weeks ago, if you do a search its covered a couple of times here on the threads. The quick temp fix is to go to the passenger side look up from under the dash and remove the fan(like three screws)while the truck is off reach up into the system and i'll bett theres a flat piece of plastic thats broken up there that you can just wiggle around and it will come out. It took about five minutes to remove it and the fan works fine but you have no way to stop fresh air from coming in until you take it to get fixed. I'm not sure if anyone has tried to glue the piece and then put it back or if it would even last, but i dont believe you can buy just that piece.

Heres the link Broke fresh air door

I need some thought on my 06 quad 1500 Big Horn:
my truck now gives foot massages!
Yesterday after the gym I had turned on my defrosters. when I turned on my fan (a/c-heater) control it was vibrating so loud that I could NOT even hear my exhaust.
Of course I had just hit 36K (36128). It was fine the last time I had driven it but all of a sudden?? this is way crazy.. any ideas where I need to start?? I have the united care care extended warranty but its a $100 deductable. Just wondering if its a simple fix or if I should just go ahead and turn it in along with my smoke at start up.. oh yeah anyone else having that problem as well??

Also can anyone provide some tips on where to start taken apart the under dash so I can check out the blower motor on the passenger side??

You guys are so good!!
It was the flappy door thingy. I did get it out and tried to glue it with epoxy. it held until I had this great idea to see if it would work the 2nd time. of course when I first put it in I tried it and it held. Oh then I had this great idea(let me varify it just in case since it took me for ever (the 15-20 mins sure did seem like forever but it really didn't take me very long) to get the little plastic thingy out that holds the motor on the end) of course I had for gotten that I had only glued it 4 hrs ago... and low and behold "snap". so I will be going and just getting a new one. its doesn't give massages ( or vibrate really bad) anymore. It started to rain so I didn't have time to take everything apart again.
Question: does anyone know what the part number is to the door flappy thingy is??

Or if they know the of a place that sales the the part besides the dealership..

my truck would smoke when i first started it but wasent bad i replaced thepvc valve and the smoke went away . you might try that

thanks you very much i really appreciate that. I will try.. have a great day!

I just called my dealer they want $440 just to change the fresh air door The pats department said the door {flap} goes for $24. I took the broken door out altogether and all my vents work with heat & A/C, Its just getting fresh air in the cabin all the time, doesn't bother me, any one else have this problem and fix it without removing the dash? thanks.....