Blower bust

mjt · 5 Dec 2011 at 07:35

Don't you just love old BMWs? :rolleyes:

So the vents/heater/fan/whatever was going brrrrrr this morning which I thought was odd as it's not normally noisy.
Then it starts working intermittently, and now it's packed up. All in the space of 15 minutes.

Before it died, there was a pause before it kicked into life.
Now it doesn't work at all. This is perfect timing considering the windows are fogged up when I get in in the morning!

So yeah, diagnosis?

paradigm · 5 Dec 2011 at 07:39

Final stage resistor... aka hedgehog.

[TW]Fox · 5 Dec 2011 at 07:45

paradigm said:
Final stage resistor... aka hedgehog.

Causing a noisey then inoperative blower? Tends to cause random behaviour rather than just nothing. I say heater blower motor.

paradigm · 5 Dec 2011 at 07:49

Final stage resistor was the cause of my work colleague's E46 M3 doing the exact symptoms in the OP.

Well I say exact, it died within a day not 15 minutes, but still.

[TW]Fox · 5 Dec 2011 at 08:16

Very unusual then - it normally causes a blower with a mind of its own, meaning the buttons don't do anything to control it anymore and it'll do random things like come on in the middle of the night and flatten the battery.

When I had exactly the symptoms of the OP - a blower that was a bit noisy and then flat out refused to work - it was the heater blower motor itself.

Makes sense to try the FSU first as it's cheap and easy, though.

paradigm · 5 Dec 2011 at 08:18

If years of racing electric RC cars has taught me anything, motors make groaning noises when they aren't recieving enough power to quite turn through the magnetic field. The FSU can cause exactly this.

I'm not saying it won't be the motor itself, but those symptoms could quite as easily be caused by something controlling power flow to the motor.

mjt · 5 Dec 2011 at 09:03

Knowing my luck it'll be both

Recently (maybe a few weeks ago? more than once) that I turned it on and nothing happened.
Then I turned it off (position 0) and back on and it kicked into life.

There's always been a bit of noise, but it's more whistling than anything, so I thought it was just the air in the vents somewhere.
Just before it died, the knob didn't do anything, and it did have a mind of its own, but literally only for a few seconds before I turned it off, and it wouldn't come back on.

Dogbreath · 5 Dec 2011 at 09:05

Does it work in any fan speed position?

mjt · 5 Dec 2011 at 09:07

Dogbreath said:
Does it work in any fan speed position?

No. Hence me thinking that it's the blower unit.
I'll have a look again in an hour just in case it has fixed itself

mjt · 5 Dec 2011 at 10:24

The whole thing's buggered, the dials are purely ornamental.
New heater is what? £2-300?

mjt · 5 Dec 2011 at 18:30

Update: it worked on the way home fine.
Popped out again now, and it's broken.

The heater works though as I can feel warm air hovering out of the vents at speed.
It's all very odd

mjt · 14 Dec 2011 at 13:12

Replaced it last week (what a complete faff removing the wiper arms was!!) and assumed all was well.

Come this morning and it stutters and groans, before not working.
Gave the centre console a disapproving smack and it kicked into life.

mjt · 28 Dec 2011 at 15:13

[TW]Fox;20722412 said:
When I had exactly the symptoms of the OP - a blower that was a bit noisy and then flat out refused to work - it was the heater blower motor itself.

Makes sense to try the FSU first as it's cheap and easy, though.

Was this a dash-out job in the E39 too?

Not looking forward to the bill for this job. They'll need the car for 3 days