My GFs 2007 Ford Escape's A/C is giving me a bit of an issue. The A/C works...sometimes. It seems to cycle every few minutes from blowing hot air then to cold air on very hot days. On other days it runs fine. I am not a mechanic but I have been mentally troubleshooting and don't think it's a refridgerant issue. I'm thinking it may be a clutch issue or a switch problem. There is no squealing from the belt and the belt looks fine. I am looking for suggestions on what, and how, to check. She doesn't want to spend a bunch of money to fix it so your suggestions will be really helpful.
FYI when it works it blows really cold air!

Thanks in advance