Nasty grinding noise turning on AC

[garrettg84]

I've had the AC on a few times in the past week with no issues. Today I heard a nasty grinding noise when turning on my AC twice. It sounded like a plastic gear grinding and losing traction against a metal gear. As soon as I touched the AC button it made an awful racket under the hood for a second or two and then got quiet on its own. I turned off the AC and did it again and it made the same noise when kicking on again. The AC blows cold and it won't make the noise again. Am I looking at some time spent in the shop in the near future or should I brush it off as a fluke?

Edit: ~14k miles on the truck.

 

[Stab]

Rodent? My dad had this problem years ago. It was a real pain repairing it after the thing had finally died! Hopefully NOT your problem!