Can someone identify the exact wire to look for.
I have exact same problem, fans work at high speed when temp gets hot but not at low speed at all when car is idling with air con on. I shorted the switch, (large round one with 2 wires coming out) where they join at the spade connectors and it made no difference. I noticed when attaching a 12v bulb to one of them it glowed up slowly. Air con takes ages to blow cold in traffic without these working unless I'm moving at high speed.