Fan / Blower motor stopped working !!

[bfaone]

My blower fan suddenly died ? The climate control panel gives full indication of fan speeds and on and off but no response from blower motor!!
I have checked my Blower fan works on its own when supplied externally with 12V through an external Car Battery.
My RESISTOR ( endstage resistor ) also works as I took out and swapped with my wife's car. It works .
Also swapped my Climate control unit IHKA with my other car. WORKS...

All the rest of the buttons on Climate control work. The fan speed display is fine....
The 12V + supply is going to the RESISTOR module. Both positive and Negative....
The Car Battery has 12.2 Volts coming to the RESISTOR unit under the blower fan when the car has no ignition.
Could some one please HELP.......

[Mineral///M4]

I just had to have both of those things replaced last week.

[Mr Gasser]

I was disconnecting the fan controls (the module with the temp controls on each side) one day fishing some cable up through there and re-plugged them when I was finished and the fan was not working...so I disconnected them again and reconnected them securely and the fan worked fine...if you did that maybe unplug and re-plug them again?

[bfaone]

Thanks.
That had happened to me earlier on when I was fitting a dash came and sourced the ACC / Ignition Supply .

It definitely not worked this time.

[bfaone]

I have located the third wire (White with brown line ) going into the endstage resistor socket along with +B (Red with stripe) and Negative wire ( Solid Brown).
This third wire , thin , is the reason for non functional fan.
I did some digging and found on the forums some guy saying that the blower fan and it's speed control works through a PWM signal.
So that simply means one thing ( since the +B 12V and earth are ALL TIME ON ) that the thin White wire with brown stripe is the wire controlling the Fan / Blower motor ( ON/OFF & Speed)

Compared and contrasted that wires supply voltage ( as I only have a multimeter and no oscilloscope)
With my wife's BMW 3 series E90.
That wire gives Negative supply ( goes low when fan is turned on ) and slides the scale 0.01V up with every step up of fan speed
Mine was not going low ( negative supply / earth )
Turned out , the same cable ( White / Brown stripe ) comes out from the black socket on the back of climate control panel. The one displaying speed and temperature and AC controls
That wire upon checking did give me a low / negative with step up 0.01V with every click of fan speed !!!
SO IT SEEMS LIKE A HARNESS FAILURE TO ME. THAT WIRE IS BROKEN SOMEWHERE IN ITS PATH.

I have put a bypass cable to have the PWM restored and Was DELIGHTED TO SEE MY FAN / BLOWER COME BACK TO LIFE !!!!!
Thanks to everyone for contributing.

I would welcome any comments about what I did , right or wrong ?

[shaun19877]

How did you bypass this ? I think I have the same issue

[MAMSport]

Interesting. I wonder where the break is? Is your car garaged or exposed to elements at night?

[JustAnotherSportsCar]

Check for recalls on your specific car. My 08 135i had a recall on some wiring for the blower motor.

[GoRomeo]

Originally Posted by bfaone

I have located the third wire (White with brown line ) going into the endstage resistor socket along with +B (Red with stripe) and Negative wire ( Solid Brown).
This third wire , thin , is the reason for non functional fan.
I did some digging and found on the forums some guy saying that the blower fan and it's speed control works through a PWM signal.
So that simply means one thing ( since the +B 12V and earth are ALL TIME ON ) that the thin White wire with brown stripe is the wire controlling the Fan / Blower motor ( ON/OFF & Speed)

Compared and contrasted that wires supply voltage ( as I only have a multimeter and no oscilloscope)
With my wife's BMW 3 series E90.
That wire gives Negative supply ( goes low when fan is turned on ) and slides the scale 0.01V up with every step up of fan speed
Mine was not going low ( negative supply / earth )
Turned out , the same cable ( White / Brown stripe ) comes out from the black socket on the back of climate control panel. The one displaying speed and temperature and AC controls
That wire upon checking did give me a low / negative with step up 0.01V with every click of fan speed !!!
SO IT SEEMS LIKE A HARNESS FAILURE TO ME. THAT WIRE IS BROKEN SOMEWHERE IN ITS PATH.

I have put a bypass cable to have the PWM restored and Was DELIGHTED TO SEE MY FAN / BLOWER COME BACK TO LIFE !!!!!
Thanks to everyone for contributing.

I would welcome any comments about what I did , right or wrong ?

That sounds more like a bad relay if the blower motor still works. 🤔