Root cause insight into the common BMW blower motor resistorfailures

On Tue, 26 Mar 2013 19:16:06 -0500, Jamie wrote:

> I can only assume the linear module at least uses a feed back to
> maintain output voltage, if it is so cheap that it does not even
> do that, then maybe they are trying to emulate a real resistor or
> they are just ****ty engineers or tightwads.

Most of the people on the BMW forums think it's one of these.

On Tue, 26 Mar 2013 19:52:26 -0500, Jamie wrote:

> Most likely thermo stress cracks due to the potting restraint.

Other people have suggested this also.

Some say the potting is what is causing the stress cracks.

Re-insert without potting, is the "said to be" solution.

One question:
If the FSU works without potting, what was the purpose of the potting?

On Tue, 26 Mar 2013 18:55:16 -0500, Jamie wrote:

>> Fluke T5-600, SKU: 133038, $109.95
> It only does AC amps..

Good catch!

On Wed, 27 Mar 2013 09:16:55 -0400, Scott Dorsey wrote:

> Can you chip off enough of the araldite from the cover to be able to
> read the numbers on it?

I will try this morning. (I was away on a trip for the past two days).

PS: Had to look up araldite:
http://en.wikipedia.org/wiki/Araldite

On Tue, 26 Mar 2013 15:51:52 -0400, tm wrote:

> Does the red jumper connect to the 40 amp fuse?

The red jumper was a hack added by one user to fix the solder cracks,
I think.

On Tue, 26 Mar 2013 15:51:52 -0400, tm wrote:

> In your other pictures, the spring clips just hold the transistors against
> the heat sink.

This implies two transistors (although I only found one).

I will dig through the mess again - but I think I was too fat thumbed
when I cut it open, and may have destroyed the evidence.

I do have a second FSU (since two failed on me) though ... but I want
to try to FIX that one (instead of destroying it).

On Wed, 27 Mar 2013 08:35:09 -0700, jim beam wrote:

>> Bomarc has reverse engineered a lot of automotive modules:
>>http://www.bomarc.org/basement/viewtopic.php?f=1&t=6&sid=8ee707756ef37b24ff5aa633 f1b4548a>
> that at least is vaguely useful

I wasn't sure how to cross reference using that list.
For example, it had only one BMW entry (camera module); and it did not have
GKR or Sitronic or Valeo brands; nor the keywords FSU, nor FSR; but it did
have things titled "blower motor controller), e.g.,

FORD F50F-19E624 heater blower motor controller ('97 L. CONNIE) 1

On Wed, 27 Mar 2013 18:37:20 -0700, jim beam wrote:

> i don't know who you think you're talking to, but i have consistently
> advocated /not/ deconstructing this unit. it's not worth it when cost
> of replacement isn't that high or you can build an alternate controller
> that will be more reliable.

Regarding cost, it seems we can get aftermarket parts for about $100;
and the part at the BMW dealership cost about $175.

Regarding repair, some have intimated that unpotting and resoldering
is a solution.

If that's true, then that might be a viable "fix".

However, I must ask: If it works without potting, and especially if the
potting is what's causing the problem, then what was the original purpose
of the potting in the first place?

On 03/28/2013 06:28 AM, Bimmer Owner wrote:
> On Wed, 27 Mar 2013 08:35:09 -0700, jim beam wrote:
>
>>> Bomarc has reverse engineered a lot of automotive modules:
>>> http://www.bomarc.org/basement/viewtopic.php?f=1&t=6&sid=8ee707756ef37b24ff5aa633 f1b4548a>
>> that at least is vaguely useful
>
> I wasn't sure how to cross reference using that list.
> For example, it had only one BMW entry (camera module); and it did not have
> GKR or Sitronic or Valeo brands; nor the keywords FSU, nor FSR; but it did
> have things titled "blower motor controller), e.g.,
>
> FORD F50F-19E624 heater blower motor controller ('97 L. CONNIE) 1
>

maybe it's similar, maybe it's not. the fact that each of the different
unit manufacturers has different internals and that they've changed over
time doesn't help you.


--
fact check required

On 03/27/2013 09:33 PM, Michael A. Terrell wrote:
>
> jim beam wrote:
>>
>> i don't know who you think you're talking to, but i have consistently
>> advocated /not/ deconstructing this unit.
>
>
> Apparently I'm talking to a blowhard troll.
>
>
>> it's not worth it when cost
>> of replacement isn't that high or you can build an alternate controller
>> that will be more reliable.
>
>
> Ass. The first step in designing a replacement is to understand what
> it is supposed to do, and how the original performed that function.

no???? really? are you /sure/ about that??? or doesn't sarcasm work
for you???


>
>
>>>> and credentials don't work on usenet - they're completely uncheckable
>>>> and many are bogus. what matters is whether you can walk the talk.
>>>
>>>
>>> You can't even crawl.
>>
>> at least i can follow a thread without being a crotchety old fart.
>
>
> Show us.

no, you're doing that.


>
>
>>>> as for having stuff in orbit, i don't have anything, but two of my best
>>>> friends do. the difference between them and you is that they're not
>>>> jaded and they're actually helpful.
>>>
>>>
>>> Then tell them to reverse engineer it for you. Or can't they 'walk
>>> the talk', either?
>>
>> i don't /want/ to reverse engineer it any more than i want to repair
>> broken light bulbs. you were the one bragging about how easy it was. i
>> said it wasn't. and when it comes down to walking the talk, you won't.
>
>
> Send me some defective modules, or quit trolling.

they're not my modules [again, you're not following the thread] and i
wouldn't replace them - i'd pwm the motor instead.


--
fact check required