2007 Golf 1.9 TDi A/C not working

I have a 1.9 TDi MkV Golf since I owned the car the A/C has not worked. I initially had the car re-gassed yet it still didn't work. Since re-gassing I have done some tests on the system and I have found that the compressor has no power but when the compressor is given power it works perfectly, I have also tested the A/C pressure sensors and they are working fine. I was wondering if there was a control unit for the A/C system, I have been trying to find information on this and all I can find is MkIV and MkVI control units. Any help would be great thanks.