Firstly as above see if the clutch is engageging on the compressor,you wont get any cold air out if its not pumping!even if your compressor is goosed internally it will still turn!second, if the clutch isnt engaging the causes are 1 clutch knackered 2 no voltage present 3 low on gas 4 high pressure switch knackered 5 ecu knackered.So save yourself some cash by seeing if that clutch is spinning(not just the pulley but both).