Root cause insight into the common BMW blower motor resistorfailures

On 03/21/2013 08:22 AM, Nate Nagel wrote:
> On 03/21/2013 10:41 AM, jim beam wrote:
>> On 03/21/2013 06:59 AM, Nate Nagel wrote:
>>> On 03/21/2013 09:55 AM, jim beam wrote:
>>>> On 03/21/2013 04:52 AM, Nate Nagel wrote:
>>>>> On 03/21/2013 06:55 AM, the will wrote:
>>>>>> Blower motor drawing too much amperage taking it out. Change the
>>>>>> blower motor anytime?
>>>>>>
>>>>>
>>>>> My thought as well. Have you measured current draw on a new blower
>>>>> motor and compared it to one that is installed in a car where the FSU
>>>>> has failed? that would tell you whether there's any merit to this
>>>>> idea
>>>>> or not.
>>>>
>>>> for an "engineer", you're simply not of this planet.
>>>>
>>>
>>> Did you have any suggestions for the OP, or did you just show up to
>>> snipe without contributing anything as per usual?
>>
>> <https://groups.google.com/group/rec.autos.tech/msg/1870e822d74b0a5c?dmode=source&output=gplain&noredi rect&pli=1>
>>
>
>
> link times out?

then use the message id within the link, retard.


>
>>
>> retard.
>>
>>
>>>
>>> You do know that most electrical/electronic components have a maximum
>>> current rating, yes? And that electric motors tend to draw more current
>>> when the bearings are going or they are otherwise subjected to loads
>>> higher than that for which they were designed? Does any of this sound
>>> remotely familiar to you?
>>
>> don't lecture me on electronics nate.
>
> 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.


>
>>>
>>> Really, what the will suggested seems to be a logical first step.
>>
>> if you don't know what the **** you're doing and don't know how to use a
>> dvm.
>>
>
> 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 ****ing retarded to
read that or understand it.


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fact check required

On 03/21/2013 04:12 PM, Bimmer Owner wrote:
> On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:
>
>> It may also be interesting to have some kind of thermometer
>> on the FSU case ...
>
> 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.


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fact check required

On 03/21/2013 08:57 AM, Bimmer Owner wrote:
> On Wed, 20 Mar 2013 23:17:36 -0700, jim beam wrote:
>
>> analyze the actual problem - don't just waste money replacing stuff.
>
> 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/sho...d.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.


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On 03/21/2013 05:01 PM, wrote:
> On Thu, 21 Mar 2013 16:59:01 -0400, "tm" >
> wrote:
>
>>
>> "Scott Dorsey" > wrote in message
>> ...
>>> Bimmer Owner > wrote:
>>>> On Thu, 21 Mar 2013 11:45:54 -0400, Scott Dorsey wrote:
>>>>
>>>>> Static resistance doesn't tell you anything, but operating current
>>>>> measured with a DMM would tell you a lot.
>>>>
>>>> It 'can' be done, but would require a test jig inserted inline
>>>> as the FSU is deeply ensconced under the dash while the blower motor
>>>> is even more deeply so.
>>>
>>> I don't know the wiring diagram on that particular model, so I don't know
>>> where you would need to break in to measure just the current of the blower
>>> without anything else. But it does not seem terribly insurmountable,
>>> especially seeing that BMW is very good about breaking everything out into
>>> connectors all over.
>>>
>>
>> Just measure the battery current with and without the blower running.
>>
>> Turn every thing else off.
>>
>>
>> QED
> Just put your ammeter into the heater blower fuse connector and you
> get the current of the blower motor.
>

what he said.


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fact check required

On 03/21/2013 05:08 PM, wrote:
> On Thu, 21 Mar 2013 22:54:59 +0000 (UTC), Bimmer Owner
> > wrote:
>
>> On Thu, 21 Mar 2013 15:03:45 -0700, Ashton Crusher wrote:
>>
>>> If it's being blown by intermittent high current draws the
>>> fuse could protect the $100 FSU.
>>
>> 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).
> 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.


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fact check required

On 03/21/2013 10:07 PM, jim beam wrote:
> On 03/21/2013 09:00 AM, Bimmer Owner wrote:
>> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>>
>>> it's cheaper to just buy a new one.
>>
>> To be clear, that's what 99.99999999% of the BMW owners do.
>> But that's not the point of this thread.
>>
>> The point of this thread is to get a handle on WHY they are all
>> failing.
>
> i already told you - it's overheating. semiconductors don't like heat.
>

Yeah, we know that.

*why* is it overheating?

>
>>
>> Specifically, how to figure that out is the question.
>
> knowing how the light bulb blew doesn't fix it.

But it may make the replacement last longer.

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Bimmer Owner > wrote:
>On Thu, 21 Mar 2013 15:16:46 -0400, Scott Dorsey wrote:
>> has anyone got docs on that mystery IC there? It's from Elmos
>> Semiconductor, but it's not a standard Elmos part number on it
>
>Focusing just on that Elmos Semiconductor AG IC from this thread:
>http://www.bimmerfest.com/forums/sho...d.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/automo...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
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 03/21/2013 07:23 PM, Nate Nagel wrote:
> On 03/21/2013 10:07 PM, jim beam wrote:
>> On 03/21/2013 09:00 AM, Bimmer Owner wrote:
>>> On Thu, 21 Mar 2013 08:14:12 -0700, jim beam wrote:
>>>
>>>> it's cheaper to just buy a new one.
>>>
>>> To be clear, that's what 99.99999999% of the BMW owners do.
>>> But that's not the point of this thread.
>>>
>>> The point of this thread is to get a handle on WHY they are all
>>> failing.
>>
>> i already told you - it's overheating. semiconductors don't like heat.
>>
>
> 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.


>
>>
>>>
>>> Specifically, how to figure that out is the question.
>>
>> knowing how the light bulb blew doesn't fix it.
>
> But it may make the replacement last longer.

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


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fact check required

On Thu, 21 Mar 2013 19:15:16 -0700, jim beam wrote:

> that's why pwm is the better solution

Does pulse width modulation cause radio EMI?

On 03/21/2013 07:39 PM, Bimmer Owner wrote:
> On Thu, 21 Mar 2013 19:15:16 -0700, jim beam wrote:
>
>> that's why pwm is the better solution
>
> 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.


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fact check required