audi tdi aircon pump / electric clutch
 

hi,
anybody out there who can help me how to get the clutch off the pump? all I can see is a central 19mm nut, but to get it off i need to somehow stop the pump from rotating (there are 3 holes that make me think there might be a special tool??)
any comments welcome...

Old fan belt round the pulley tight in a vice undo nut..







..

air con magent clutch
 

thanks, but I am not sure that's the answer - as the clutch is not "engaged" on my pump, i.e. the clutch + nut spins free within the pulley , I would still need to somehow stop the clutch from rotating....(?)