Busby2014

Hi all,
I have recently purchased a 2009 ford mondeo Titanium 2.0TDCI Auto. It only has 57,000 and has a full FORD dealer history from the previous owner on 9 years. I paid for a full independent inspection from the AA before buying with a glowing report coming back from them, and only raising that the air con wasn't working properly, but that wasn't a deal breaker for me because i just needed a reliable car for work and back. The garage regassed the aircon on requested before i picked it up and i thought nothing more of it, just happy to have a reliable car after my previous MINI kept breaking down on me (weekly). Since the hot weather I have noticed that the aircon doesn't work at all. I was away last weekend and dropped it into my local garage i use for all my work. They tested the system and said it was fully gassed with no leaks, but couldn't diagnose the problems themselves. Button in the cabin looks like its working, but when the aircon light come on the motor doesn't kick in. They said they could start replacing parts but it would end up costing a fortune and recommended taking it back to FORD to get it diagnosed, then if i wanted to, take it back to them to repair (which is fair enough cause i don't want unwanted costs).

Has anyone else experienced this and what could it be? Are there common faults I should be aware of ?