I have an annoying problem with the air con on my focus, just wondering if anybody has any ideas as to what it could be?

Basically the problem is that it randomally cuts off? It always works when you first get in the car and sometimes lasts for days before the problem happens again.

When it does happen normally you just give it a few minutes and try again and it works again?

I had a similar issue a couple of years ago which was the compressor clutch working intermittently, I changed it for another one from a breakers and it worked ok. When the clutch was playing up you could always hear the condenser fan running, with this latest problem when the ac cuts off the fan stops too leading me to think it could be some kind of pressure issue?

Anyone got any ideas or things I can check to try and find the problem?