Hi Guys,
Called to a MTA chiller with both systems out on High Pressure switch. Its a R407C chiller with two systems.
No wiring diagram of course!

There are 4-off HP switches, two per circuit, one manual and one auto.
The switches are wired in series and there is 220V all the way through the switches. The HP relays are energised.

Here is the kicker.
I removed the fuse from the 220V transformer as I wanted to check wiring etc, put fuse back in and circuit one starts up. Look at the Carel controller, but still get an HP switch alarm on circuit two.
Just so I wasn't going mad, when the circuit stopped on temperature, I removed the fuse again, put it back in and Circuit two starts and circuit one is no alarmed on HP switch.
So now I am really going mad.

Anyway left it for tonight to see if I can find a wriring diagram.

Its a MTA AS319/N chiller.

Any thoughts?

There is another thread on here "MTA Chiller HP switch fault" with exact same problem, but looks like that issue was sorted with a fuse in the transformer.