
It's a 2006 Toyota Avensis with an oveheating issue. This model (from what the workshop manual says, anyway) shoud have a dual-speed fan. The wiring for low-speed operation is missing entirely, which leads to the car overheating in traffic. The engine itself is fine, but the starter, which I suspect is a cheap off-brand replacement, hates it, and will refuse to operate when too hot (I believe the solenoid on it is the cause, it does not "click", it does get power ok). In situations with airflow (speeds above 30mph) it is fine.
After looking at the diagram of how it "should" be, and relocating some components to minimise the extent of wire splicing, I have come up with this diagram. Does it look plausible?
I may wire "low speed" to a physical switch, or the headlights or something, as I do not want to further hack the AC wiring on this car, as it is poor. (the car cost 800€ and it's a stop-gap vehicle, I'm surprised it lasted this long)