Compressor Clutch Won't Energise

[white lancer]

BMW X5 3.0i Sport 2004 Auto

My Air Con has never worked since I bought my X5 but due to the recent warm weather I though about getting the system checked out to get it fixed. I was outside in the carpark yesterday and there was one of those mobile air con engineers re-gassing another car so I asked him to take a look at mine when he had finished.

He checked the gas pressure and said it was fine. He did connect the bottle and guages anyway for testing. he said to me the compressor clutch is not energising. he checked the fuses and then put a hotwire on the clutch which energised and the compressor started working pumping ice cold air into the car.

He spent another 20 minutes or so trying to find out what the problem was. he said all of the components seem to be working fine but the compressor clutch wont energise when you press the snowflake button in the car? He said to me that there seems to be an electrical problem? he also said that the condenser fan at the front of the car was supposed to be running but it did not.

The mobile air con engineer then said that he was at the limit of his electrical ability and I needed to take the car to a BMW garage to get it sorted?

Does anyone have any ideas as to where I can look next? I dont have an electrical diagram to check but I was thinking that maybe there was a relay in the curcuit somewhere which i can check?

The heater and blower work fine and I can change the temperature and speed etc

thanks for your help in advance.