Air Conditioning Compressor Check

[JefferiesFarnol]

Hello Chaps,

My leaking condenser was changed earlier this year and the system still has pressure but the a/c doesn't work. As per a previous thread, I've been through the whole cooling fan process and fixed that, the fuse is fine and I've swapped the relay with the identical fog light one and they both seem to work so I've been led back to the compressor.

I wonder if anybody could tell me how to check if the compressor clutch is engaging? Some pictures would be helpful if at all possible as I really don't know what I'm looking for, whether it's on or off I can't really see any difference.