75 AC Fan wiring

[GTVeloce]

For some reason my 75 has decided that when the AC compressor switches on it doesn't also engage the engine fan. The engine fan works fine to regulate the engine temps. There are two relays near the coils in the engine bay that control the fan and the compressor however, I can't for the life of me work out (from the wiring diagram) how the relay for the compressor switches on the fan. I am quite certain this used to work but now it doesn't. To cope in the hot weather I have just joined the two outputs of the relays which means my AC works fine but also means whenever the engine fan kicks in it turns on the AC!

I have attached the wiring diagram in question but am struggling to understand how it should work. Any guesses?

[bazzbazz]

Need the key guide that goes along with it to read the diagram.

The list that tells you what P2, L6, Q11, and so forth are.

[GTVeloce]

To put some closure on this; I did manage to work it out form the diagram. Given a) the compressor was engaging when requested and b) the engine fan was cycling as needed to regulate engine temperature, I was able to deduce the trouble must have been the white wire (B) that runs between the trinary switches (Q20) and the radiator temp switch (L6). After removing all the stuff in the way I found a white wire that had pulled out of its connector. A new connector and hey presto she works again.