Weird AC Noise Issue

[2009Exp]

I am having a weird issue with my Air Conditioning making noise.

My truck is a 2009 Ford Expediton XLT with 22,000 miles.

When you turn the key to the on position, it makes a tapping noise. This sometimes continues for a while if its on all the way cold. A YouTube video is below of the issue. If you adjust the temperature from all the way cold, the noise stops. However, if you put it back on all cold, it starts up again.

Also, it just had the 20,000 mile service done. It started doing it after that.

http://www.youtube.com/watch?v=uH0-ipe_tQA

Do you guys have any idea what is causing this? Would I be able to fix it myself? Thanks.

Also, my air is not that cold. Would this be related?

 

[walnuts4x4]

i'm wondering if you have a problem with the blend door.. maybe part of the hinge is cracked and when the door is all the way closed on cold it is making the noise and when you move the door it stops making the noise.....

 

[toms89]

My guess is there is a problem with the electronic door actuator. This controls the blend door. Have no idea where it is located on the 2009 expy. Could be a nightmare to get to.

 

[SOLISIMO]

Dude with something that obvious I wouldnt be posting here and taking that to the dealer! Holy Crap..... thats loud.