The other day my heater fan decided to stop working and I can't seem to get to the bottom of it.

Everything on the heater control unit works - air con + recirc. buttons, temp. dial, blower position dial - but nothing from the heater fan dial.

I've checked the following with a multimeter, with the ignition on and off, and whilst adjusting the fan dial, and found them to be fine:
- 2 x 'heater blower' fuses in fusebox (fuses intact, power going to sockets)
- relay behind glovebox (swapped with fuel pump relay and all good)
- resistor that bolts into the a/c box behind the dash (has power and clicks when dial is adjusted)
- power going to the heater control unit
- removed fan and tested that it spins (didn't 'hotwire' it to test it due to lack of available fused wire)

The only thing that isn't correct is that there's only 0.6v going to the fan, regardless on dial position. Presumably the power going to the fan is determined by the resistor, so the resistor itself must be bad, even though it clicks when the dial is moved?

Bonus question, any idea why the below bodge job behind the heater control unit has been done? It seems to leave a loose red wire to which I can't find the other end! The blue wire is spliced into another (presumably 12v live) wire that goes from the ignition to the fuel pump..! That said, it hasn't caused a problem for the two years I've had the car, and I don't believe it's the root of my blower issue.



Thanks in advance!

 

Cant help - but here is the wiring diagram for the A/con (my99/00, but should be similar)

If you cant read it let me know and I will try an 'attachment' instead

 

Thanks, very helpful!