Originally Posted by Juttie
Just had a quick look and if I run a positive from battery to.pulley it operates so guess next thing is to see what voltage I have at relay I guess.
Good news, some progress
The relay has permanent 12V to its coil and other end of the coil is "pulled" to ground by the ECU.
There are two fuses, one for the compresser feed (one of those in main fuse box in engine bay, #4 10A) and another for the relay (multipurpose #5 - they are the bank of plug in fuses in the J/B fuse box under dash). (hope I've read those correctly !)