blower motor on full all the time

Hi all.
I have a 1.4i 2004 c3.
It has the digital climate control.
First we had an issue where the blower motor would intermittently come on and off if we went over bumps, mainly on the left hand side.
I had a garage look at it and was told the motor was gone. I am hardly so put it on my to do list. For a month the motor never came on again until one morning when I first started the car it came in with a mighty racket! Then nothing, but a mile up the road smoke started pouring out from under the glove box.
I quickly stopped the car and pulled the main fuse F18. When I removed the motor it was really chewed up so I think it was not put back in properly by the garage.
I bought a new motor and replaced it but now when the engine is on. The motor is on full! Controls have no effect.
I have replaced the resistor pack, exchanged with another digital control unit but still the same, on full.
I even removed motor and tried a bulb but that stays on with no response from the controls.

I am lost what to try next.
I have another resistor pack on order incase I was sold a faulty one but not too optimistic.

I can't see any obvious shorts in the plugs either.
Hope you can help.

Hi

Owen Reynolds wrote: ↑Tue Nov 30, 2021 7:46 pm Then nothing, but a mile up the road smoke started pouring out from under the glove box

When you let the smoke out, it never works properly.

You could have melted the insulation on some wires somewhere and now the conductors are shored together

Check for shorts.

I've run a multimeter across the terminals to the motor and get 14 v (engine running) power In to resitor pack is same. It's as is the resistor pack is being bypassed.
I know these things work by increasing the ground voltage to slow the fan down?
Does anyone have a circuit diagram of this, I bought a Haynes manual but does.not include climate control model.
Could the relay that supplies the power when engine running have shorted? Wouldn't make sense though. Is there way to confirm the feed from the control unit is OK?

Owen Reynolds wrote: ↑Tue Nov 30, 2021 8:18 pm Does anyone have a circuit diagram of this

You may need to click/tap the image to see a clearer version of it.

Thank you for the circuit diagram
I'm even more confused now. This doesn't seem to match what I have either. This shows a direct feed from the control unit to the motor.
Mine has two thick wires, brown and black into the resistor pack p/n 6441.L2 type. Then a plug with thick red and brown to motor and two thin black and brown, which I assumed came from the control unit but not confirmed.
This has only 4 wires from the control unit to what I think is the resistor pack.

Sorry Arfur that's the wrong diagram. That's the plain-vanilla version

Here is the circuit diagram for the digital version. There is a fault in the diagram. 8085 and 8045 are the same thing...the electronic fan controller.
8050 is the fan and 8025 is the digital control panel.
Power and ground come into the fan speed controller on the 2 pin connector. The digital control signal and the output to the fan are on the 6 pin connector.
I believe your problem is a short from the fan controller power wiring to the fan wiring, as Arfur says.
The fan draws a lot of current and so wiring problems are not uncommon.
The speed controller uses a large FET (field effect transistor) to run the fan. Typically this goes open or short circuit. Seeing as you have replaced the speed controller but the fault remains AND the fault was intermittent, that leads me to believe the fault is somewhere other than the speed controller.

Thanks guys, super support.
So would I be right in saying that if I plug a new "resistor pack" in, and the short remains I could goose the new one!

Just another thought. If there is a short on the wire from the pack/fan controller then would the fan not work? My issue is the fan is always on?? Confused.

Owen Reynolds wrote: ↑Wed Dec 01, 2021 5:32 pm Just another thought. If there is a short on the wire from the pack/fan controller then would the fan not work? My issue is the fan is always on?? Confused.

If the fan supply live was shorted to any permanent or switched 12v after the smoke incident, then the fan would stay on all the time the wire it is shorted to is live.

One thing I have done is disconect the controller/pack then the fan does not come.