Octavia vrs 06 air con solenoid/valve fault.

Hi guy/gals I have just bought a 06 octavia vrs diesel, I'm loving the car but having a prob with the aircon! When a mechanic looked at it he said it was the solenoid/valve on the compressor, I have a friend who is a very experienced a/c engeneer coming to look at it tomorrow, I just wanted to know is it possible to change the valve without changing the compressor? And if I remove the comp and comp belt can I run the car with it off whilst we repair the part? All help will be appreciated.

Thanks