Thanks for this; good to know.

New compressor should be arriving tomorrow, the guy says he'll put UV dye in the system so as to reveal any leaks.

Fingers crossed....

R

 

I could not find mine with the UV light. when I checked initially

 

So I now have working A/C - yay!
The cause was indeed the compressor. Nothing to do with the CAN bus at all! Perfect example of how software can lead you down the wrong path.
However, there's still the leak to find, which may be the hose union on the top of the drier (it already has a yellow ring round it from the dye).
But it's progress I suppose....
The cost was eye-watering, of course. Here, when it's a particularly big bill, they present it to you in a special cardboard wallet. So yeah, I got the VIP treatment in that regard!