After a brief search nothing came up. So here is the problem. We have an 07' f150 XL that we use here at work. Just in the last few months, my dad has started to notice a tapping sound under the dash. If you move the a/c temp **** toward cold it will stop. I have just pulled out the glove box to trace it and after hearing it while looking for the problem, i have felt the tapping on the plastic box behind the glove box. It taps about 2 times per second and sounds like plastic on plastic. Any ideas on what this is and how to fix it?

 

Sounds like it could be the blend door actuator. Do a google search on that, i believe it's a fairly common issue

 

My truck does the same thing. If I turn it to all the way cold or hot it will stop. Anything in between and it will make this annoying noise. I'll have to look into it once I get all of the other problems resolved.

 

Thanks for the feedback. I will be looking into that area soon.