Clicking from under the hood

[gp5346]

Edit: I've narrowed it down to the AC compressor.

There's a strange clicking coming from under the hood of my 99 Explorer.

http://www.youtube.com/watch?v=dIu91faBSE0

It happens while running idle, not sure if it occurs while accelerating.

Whats wrong with it, how do I fix it, and can I still drive it without damaging it further?

 

[deweyville65]

The only click I hear is your A/C compressor clutch activating. Totally normal

 

[gp5346]

Doesn't it seem to be cycling kinda fast? From what I gather, maybe it needs more freon? Something about the pressure being out of whack, due to low ambient temps.