Root cause insight into the common BMW blower motor resistorfailures

[jim beam]

link times out?

then use the message id within the link, retard.

ooh, or what? ITG gonna kick my ass? Sorry, I'm more interested in
helping the OP than your delicate little feelers.

no, don't lecture me on stuff that you clearly don't have the first clue
about.

see above. retard.

WTF is that supposed to mean?

it means that, if you know what you're looking at, a dvm can tell you
most of what you need to know here.

OP can dissect the thing all he wants but it doesn't do him a damn bit
of good to know *what* has failed unless he knows *why* it failed.

all he needs to know, retard, is that the unit failed and that he needs
to replace it. just like a light bulb.

more than that though, i also told the op how they can go about
establishing a permanent solution, but you're too fucking retarded to
read that or understand it.

 

[jim beam]

That seems like an EXCELLENT idea,

won't save the unit, just a frozen motor.

if we can put some kind
of temperature indicator in the FSU tines, then we can observe
what the temperature is in situ - which might tell us something
about what is overheating these things (assuming heat is the culprit).

you can run the unit out of the fan housing - hold it in your hand and
you'll soon find out if it's getting hot or not.

 

[jim beam]

That's exactly what we've done - yet - we need help since nobody to
date has figured out HOW to test an FSU that is fried.
http://www.bimmerfest.com/forums/showthread.php?t=678534

it's like testing a dead light bulb.

Note: It appears to be an active component, but it probably does
dissipate 100W.

it dissipates Vd x Im where Vd = voltage drop across the unit output,
and Im = current drawn by motor. it will indeed get hotter when running
the motor slower because of the greater voltage drop across the unit.
that's why pwm is the better solution - the semiconductors are either
fully on [minimal heat dissipation] or fully off [minimal heat
dissipation]. the only time they get to dissipate heat is during
switching which is a sub-millisecond event and a tiny percentage of the
base time.

 

[jim beam]

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

what he said.

 

[jim beam]

So the crafty germans are using a high tech solid state resistor
instead of a PWM speed controller???

If I had one and it blew I think I'd be designing a PWM controller to
take it's place. Need to find out what kind of signal the controller
expects, but that shouldn't be too difficult.

indeed.

 

[Nate Nagel]

i already told you - it's overheating. semiconductors don't like heat.

Yeah, we know that.

*why* is it overheating?

knowing how the light bulb blew doesn't fix it.

But it may make the replacement last longer.

nate

 

[Scott Dorsey]

Focusing just on that Elmos Semiconductor AG IC from this thread:
http://www.bimmerfest.com/forums/showthread.php?t=309399
It looks like the PN is ELMOS, 10901D, 667A 1302A

It might be a generic or a special chip; I can't find it on the web:
http://www.elmos.com/produkte/automotive/motor-control/dc-motor-ics.html

All the standard Elmos part numbers begin with an E.

My guess is that the number on the chip is 10901D and that the other
two numbers are date and batch codes.
--scott

 

[jim beam]

Yeah, we know that.

*why* is it overheating?

because it's linear, retard. if you don't know what they means, ****
off until you find out.

But it may make the replacement last longer.

putting facts in front you dumb ass all day long doesn't make you any
smarter.

 

[Bimmer Owner]

that's why pwm is the better solution

Does pulse width modulation cause radio EMI?

 

[jim beam]

Does pulse width modulation cause radio EMI?

it can if the radio isn't very noise resistant and the switching is
"hard". you won't typically hear it on the fm bands, but you might on
the am.

you can make a pwm unit "soft switch" and kill pretty much all of the
electrical noise it would otherwise generate and incur only a very small
heating penalty.

 

[Nate Nagel]

because it's linear, retard. if you don't know what they means, ****
off until you find out.

so "because it's linear" it by nature overheats to the point of failure?
Odd, I'm pretty sure that that controller worked initially on, well,
all of the vehicles in which it was originally installed.

The question is, is it overheating to the point of failure because the
designer cut things too fine (in which case designing a better part
would be the right approach), or is it because there's another issue
somewhere else *causing* a part that would otherwise have acceptable
service life to fail (in which case replacing it with a stock
replacement and fixing the underlying issue would be the most economical
thing to do)?

putting facts in front you dumb ass all day long doesn't make you any
smarter.

IKYABWAI.

It would really be just like you to spend all day designing a more
robust controller, building it, watching it too burn up, and then
realize that the problem was something else, like a chronic problem with
dry fan motor bushings, windings dragging on the case, something like that.

But sure, don't check the obvious stuff, just go into your long-winded
sometimes technically correct and sometimes not babble, I know that
anything I say won't stop you anyway.

nate

 

[Scott Dorsey]

because it's linear, retard. if you don't know what they means, ****
off until you find out.

Nothing wrong with linear motor control, it's just inefficient and
produces a lot of heat. I used to work in a place with a 1.2 MW DC
motor whose field coil voltage was controlled by a couple rooms full
of cast-iron resistors. The resistance array lasted nearly 80 years
before the whole facility was taken down.

As long as you keep within the safe operating area of the semiconductors,
you're fine. If you exceed them, bad things happen. But we don't know
if the semiconductors are failing on these things, or if it's just
ordinary RoHS solder failures; the RoHS crap doesn't like thermal cycling
so well.
--scott

 

[Scott Dorsey]

Does pulse width modulation cause radio EMI?

It can if it's not properly filtered. And the reason why I think beam is
correct about this being a linear control is that there is no filtration
in there.

My guess is that the cost of proper filtering and shielding makes the pwm
controller cost more than the linear controller in this case, which is
probably why they went the linear route.
--scott

 

[jim beam]

On 03/21/2013 07:53 PM, Nate "anosognosic" Nagel bleated:

It would really be just like you to spend all day designing a more
robust controller, building it, watching it too burn up, and then
realize that the problem was something else,

um, no, it would be me building something that worked first time. and
that has stayed working.

but you wouldn't know that because you're an unspeakable hamster brained
retard that hasn't got the slightest clue the **** they're talking
about, much less the ability to click on a link and READ it.

like a chronic problem with
dry fan motor bushings, windings dragging on the case, something like that.

which are entirely fucking different, and don't fucking disappear after
the controller has been changed.

But sure, don't check the obvious stuff, just go into your long-winded
sometimes technically correct and sometimes not babble, I know that
anything I say won't stop you anyway.

i wish something would stop you. like self-awareness.

 

[jim beam]

Nothing wrong with linear motor control, it's just inefficient and
produces a lot of heat.

right, but what's the point in using 140W to run a 60W motor? and
/certainly/ not when the devices to do so are so cheap and abundant. i
can see doing it back in the day when there weren't any other options,
but today there are, and there have been for 20+ years.

I used to work in a place with a 1.2 MW DC
motor whose field coil voltage was controlled by a couple rooms full
of cast-iron resistors. The resistance array lasted nearly 80 years
before the whole facility was taken down.

As long as you keep within the safe operating area of the semiconductors,
you're fine. If you exceed them, bad things happen.

right. but again, we're dealing with mba's here. as an engineer,
you're going to design with reliability and a safety margin built in.
as an mba, you're going to cut and keep cutting until it meets "business
objectives".

But we don't know
if the semiconductors are failing on these things, or if it's just
ordinary RoHS solder failures; the RoHS crap doesn't like thermal cycling
so well.

very true. but at the end of the day, that's still heat. and a linear
semiconductor controller is just stooopid when a wire coil will do the
same job more reliably and at a fraction of the cost.

 

[jim beam]

It can if it's not properly filtered. And the reason why I think beam is
correct about this being a linear control is that there is no filtration
in there.

it's the heat sink that's the dead give-away. a pwm controller heatsink
would be 1/10th the capacity. or less.

My guess is that the cost of proper filtering and shielding makes the pwm
controller cost more than the linear controller in this case, which is
probably why they went the linear route.

i think the cost of that honking great heatsink significantly exceeds
the cost of a couple of extra inductors and caps.

 

[Bimmer Owner]

Just put your ammeter into the heater blower fuse connector and you
get the current of the blower motor.

That's an interesting idea.
http://www3.picturepush.com/photo/a/12475041/img/12475041.jpg

The fuse for the blower motor is called the "infamous F76" for a reason.
http://bimmerfest.com/forums/showthread.php?t=674612

It's a 40 amp fuse under the glovebox but it's in a really inaccessible
spot; however, it's right side up, so, the wires going INTO it are
visible from the tips of your feet under the glove box.

So that's a possibility; but you'd have to cut the wires.
http://www5.picturepush.com/photo/a/12475043/img/12475043.jpg

 

[Ashton Crusher]

That's an interesting idea. The FSU supposedly consumes the
most power when the blower motor is set to the LOW settings
(simply because it has to dissipate the power as heat), so,
we could prevent excess current by fusing... say with a 10A
fuse, the blower motor (which is said to consume 5 to 6 A).

Hmm, it did look like it had quite a heat sink. I had assumed it used
PWM to change speed, which should not generate much heat but my
assumption might be wrong (or my understanding of PWM...) A solid
state design that gets hot on purpose seems like a poor design to me.

 

[[email protected]]

All the standard Elmos part numbers begin with an E.

My guess is that the number on the chip is 10901D and that the other
two numbers are date and batch codes.
--scott

If you google for 10901D it comes back with hits to
Chinese chip brokers that show it as an Elmos 16
pin surface mount chip. Which is consistent with what's
in the picture of the failed module, it has 16 pins.
But I could not find any data sheet on the part either.

 

[Bimmer Owner]

If you google for 10901D it comes back with hits to Chinese chip brokers
that show it as an Elmos 16 pin surface mount chip.

I found the same. The chip is listed here:
http://www.jotrin.com/product/parts/10901D

But there is no datasheet there.