It just recently started, but my AC stopped blowing cold air, at one point it felt like the heater was on. I opened the hood and I could see the compressor clutch would engage, then disengage every few seconds. However, once I'm driving around, engine in a higher rpm than idle, the air gets cold. Im sure the belt isn't slipping. What would cause the compressor to kick on and off repeatedly? Could it be low on freon? I believe it only does it at idle.

 

Could just be low on Freon.

 

+1
low charge levels will cause the system to short cycle.