Hello, the AC clutch on my 2001 S80 2.9 isn't receiving power with the AC switch on under normal operation, but a jumper wire from the positive terminal near the engine bay fuse box to the compressor engages the clutch. I know low refrigerant pressure will cause a pressure switch to open and not send power to the compressor, but I want to find what exactly is opening the circuit.

In my limited understanding, the circuit is as such:

Battery -> relay in fuse box turned on by AC switch -> low (high?) pressure switch -> thermal switch (which I found in this thread)-> Compressor -> ground.

Where is this circuit incorrect? Also, where are the switches located?

 

there is also fuse that protects clutch form short circuit.
There is no low(high) pressure switch. The relay is controlled by ECU using pressure sensor and thermal sensor on the condenser (not so straightforward but close to it).
Fuse is number 8 in the engine compartment.

 

So the circuit goes...

Battery -> Fuse -> Relay in fuse box controlled by ECU -> thermal switch -> Compressor -> ground

Correct?