So I know it's a stupid question because I hate it when people try to explain a noise coming from there vehicle but I got a VIDEO it sounds like its coming from somewhere closer to the bottom of the engine. It's starts and goes away then comes back as you can see in the video. I had it in the shop for something else and I asked they guy to check that out to and said he didnt hear anything -_- ... How he didnt idk but any advice or ideas would help thanks. It's a 99 5.4 with 107000 miles on her.
http://www.youtube.com/watch?v=v1DSqDBTWU4&sns=em

 

A/C pump/clutch bearing. Let me guess, your using your defroster?

 

Yep I agree with Toyz if it cycles like that it's most likely the AC clutch.

 

Yeas, I went out there and had the air off and it was a constant sound but when I turn it on it cycles like that