Regarding the PCB
: it's inside the black box. It's the board that the thin wires are connected to. Basically, I need to see the other side, which I think is what you are asking about, and calling a panel. It's sort of greeny yellow brown.
Do you know whether Keiths was for a diesel or a petrol. I suspect a diesel as he was (is) also the FBH (Fuel burning heater.)
meister. That would confirm yours is a diesel one in spite of my suspicion.
What's worse, even the pictures of the 'before' don't correspond properly to the circuit diagrams given in the Rover workshop manuals, so the circuit diagrams are proving worse than useless because it means I'm giving you duff advice.
Do you think it can wait until the Nano? If we use your existing relay box, it doesn't matter if the one with the new fan is right or not. Once I can get a multimeter on the thing, and look at what connects where on the big multiplug it will become clearer.
We can check the fan itself by disconnecting it from the box that came with it: disconnect the thick wires that go to the fan and resistor, three of them. If Jules is correct (and he is experienced in this) then connect the brown that goes to red to the plus. The wire with the resistor in it connects to negative for low speed. The other wire connects to negative to give high speed. Watch your fingers, and don't allow anything to get into the fan for gawds sake. In particular it will suck that gravel drive through and make a mess of something or lots of things.
BTW, there are a fair few technical advisors who are there to help over on the OC, as I think you are active there too. Surely one of them knows about this? Might also be worth asking Jules himself as he has direct experience of this.
The problem with testing the fan is I'm not sure about the differences to the new system. You can find out whether the fan itself is OK, by disconnecting it from the black box. I'm struggling to give you reliable advice, now it's clear the circuit diagrams are wrong in so many ways.