Does anyone have insight into what is the root cause (and repair) of the
FSU failure that plagues almost every 1997 to 2003 BMW?
http://www.bimmerfest.com/forums/att...0&d=1194115994

Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
or by FSU (Final Stage Unit), is known to fry itself in almost every single
E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
http://www.bimmerfest.com/forums/sho...d.php?t=143393

The problem with replacing this ~$100 part is that the new replacement FSU
fries itself just as often as the old one did, so you end up repeatedly
replacing your fried FSU every few years or so.
http://www.bimmerfest.com/forums/sho...d.php?t=528566

That's fine for most people (although the DIY is a PITA) - but I ask
this newsgroup whether anyone has any insight into WHAT is actually
breaking - and - why?
http://www.bimmerfest.com/forums/sho...d.php?t=309399

Here is the best (admittedly sketchy) wiring diagram we have so far:
http://www1.picturepush.com/photo/a/...g/12467819.png

On 03/20/2013 08:08 PM, Bimmer Owner wrote:
Does anyone have insight into what is the root cause (and repair) of the
FSU failure that plagues almost every 1997 to 2003 BMW?
http://www.bimmerfest.com/forums/att...0&d=1194115994

Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
or by FSU (Final Stage Unit), is known to fry itself in almost every single
E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
http://www.bimmerfest.com/forums/sho...d.php?t=143393

The problem with replacing this ~$100 part is that the new replacement FSU
fries itself just as often as the old one did, so you end up repeatedly
replacing your fried FSU every few years or so.
http://www.bimmerfest.com/forums/sho...d.php?t=528566

That's fine for most people (although the DIY is a PITA) - but I ask
this newsgroup whether anyone has any insight into WHAT is actually
breaking - and - why?
http://www.bimmerfest.com/forums/sho...d.php?t=309399

Here is the best (admittedly sketchy) wiring diagram we have so far:
http://www1.picturepush.com/photo/a/...g/12467819.png


that looks like a linear semiconductor controller - an incredibly
antiquated concept for a modern car.

old resistor packs for fans were open wire that sat in the fan's air
stream for cooling. they were generally very reliable if their alloy
wasn't too susceptible to salt.

that unit looks like it still sits in the air stream with that honking
great heat sink and i estimate it's trying to dissipate 100W. that can
only mean it's a linear controller because a modern pwm device can
control high motor currents with very little heat dissipation 10W.

bottom line, a linear controller is always going to get hot and end up
frying itself over time. the only thing you can do is either replace it
with another unit that will ultimately meet the same fate, or undertake
a significant modification.

for the latter, you can try putting an even bigger heat sink on it - but
i doubt there's a lot extra room available. you can also "pwm" it. i
built a similar unit to deal with a linear controller over-heat issue on
my 89 civic.

http://www.flickr.com/photos/38636024@N00/5068043855
http://arduino.cc/en/Tutorial/PWM

depending on how much time you want to spend on a project like that, pwm
can control superbly and offers benefits like motor speed not being so
susceptible to supply voltage [engine idle voltage drop] etc.

the down side of pwm is that it can generate electrical noise. [poor
stereo installations can be particularly susceptible.] the ideal
solution is to implement pwm with "soft switching", but that's getting
quite advanced.


--
fact check required

On 03/21/2013 03:55 AM, the will wrote:
Blower motor drawing too much amperage taking it out.

if it were an adequately designed unit, it should tolerate that and worse.


Change the
blower motor anytime?

analyze the actual problem - don't just waste money replacing stuff. a
$30 dvm will diagnose this for you, and you should already own one if
you have any ambition to repair any modern vehicle.


--
fact check required

Blower motor drawing too much amperage taking it out. Change the
blower motor anytime?

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.

nate

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

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.

My inclination is to do exactly the same thing I do with the cooling system
issues: blame German engineers who seem to believe that their climate is
typical of the entire world.

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure. Put a bigger transistor
in there.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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.


--
fact check required

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?

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?

Really, what the will suggested seems to be a logical first step.

nate


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

On 03/21/2013 06:47 AM, Scott Dorsey wrote:
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.

My inclination is to do exactly the same thing I do with the cooling system
issues: blame German engineers who seem to believe that their climate is
typical of the entire world.

that's not going to fix it though. and the germans sell a LOT of these
vehciles in the middle east - it's a good deal hotter there than here.
they know exactly what they're doing.



I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure. Put a bigger transistor
in there.

unpotting is a nightmare - it will take much less time to build your own
pwm controller. who knows, maybe you can switch the existing unit???!!!


--
fact check required

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

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.



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.


--
fact check required

On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure.
Put a bigger transistor in there.

Here are pictures from the last half dozen who tried that approach:
http://www2.picturepush.com/photo/a/...g/12470740.jpg
http://www4.picturepush.com/photo/a/...g/12470742.jpg
http://www2.picturepush.com/photo/a/...g/12470745.jpg
http://www4.picturepush.com/photo/a/...g/12470747.jpg
http://www5.picturepush.com/photo/a/...g/12470748.jpg
http://www2.picturepush.com/photo/a/...g/12470750.jpg

Most who try to unpot fail, mainly due to damage caused to the
surface-mount circuit board during the initial mechanical degooping
step.

Those deft few who avoid knocking off the surface-mount components
with the debriding chisel, are left with a badly bruised board,
where some have said they've resoldered solder cracks (see pics).

One problem with "put a bigger xtor" is that nobody on this planet
has produced a decent circuit diagram of the FSU.

Does anyone here have access to an FSU circuit diagram?

On 03/21/2013 08:04 AM, Bimmer Owner wrote:
On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure.
Put a bigger transistor in there.

Here are pictures from the last half dozen who tried that approach:
http://www2.picturepush.com/photo/a/...g/12470740.jpg
http://www4.picturepush.com/photo/a/...g/12470742.jpg
http://www2.picturepush.com/photo/a/...g/12470745.jpg
http://www4.picturepush.com/photo/a/...g/12470747.jpg
http://www5.picturepush.com/photo/a/...g/12470748.jpg
http://www2.picturepush.com/photo/a/...g/12470750.jpg

Most who try to unpot fail, mainly due to damage caused to the
surface-mount circuit board during the initial mechanical degooping
step.

Those deft few who avoid knocking off the surface-mount components
with the debriding chisel, are left with a badly bruised board,
where some have said they've resoldered solder cracks (see pics).

if people priced their time and ignored the damage in which attempts to
unpot invariably result, it's cheaper to just buy a new one.



One problem with "put a bigger xtor" is that nobody on this planet
has produced a decent circuit diagram of the FSU.

Does anyone here have access to an FSU circuit diagram?

you don't need it any more than you need the circuit diagram of a chip's
internals - all you need is its function parameters - which you pretty
much already have.

you might be able to pwm the unit itself thus pretty much removing the
heat component thereby prolonging its life [literally] exponentially.


--
fact check required

On Thu, 21 Mar 2013 03:55:47 -0700, the will wrote:

Blower motor drawing too much amperage taking it out.
Change the blower motor anytime?

This is an interesting approach, given that the vast majority of
bimmer owners do NOT replace the blower motor - they replace the FSU.

While the blower motor replacement procedure is a major PITA, one
'can' test the leads from the FSU harness connector pins #5 and #1
which are power and ground respectively to the blower motor.

Again, we don't have a circuit diagram, but it has been said that
the blower motor takes about 6 amps (variously, depending on the speed)
but it would take a test jig to test that in operation.

To my knowledge, nobody has created that test jig (although I know
of only one attempt, which failed):
http://www.bimmerfest.com/forums/sho...&highlight=fsu

It's easy enough to test the resistance of the blower motor though,
and those results have come out at about 0.4 to 0.6 ohms.

It would be expensive to change a blower motor on a whim, so, how
would YOU suggest the blower motor be tested in situ?

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?


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.


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?

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.

nate

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

Bimmer Owner wrote:

It's easy enough to test the resistance of the blower motor though,
and those results have come out at about 0.4 to 0.6 ohms.

Static resistance doesn't tell you anything, but operating current measured
with a DMM would tell you a lot.

It would be expensive to change a blower motor on a whim, so, how
would YOU suggest the blower motor be tested in situ?

I've never tested one, but I put a drop of turbine oil on the motor bearings
every five years or so. I do the same on the window and seat motors too.

I'd imagine if you listen carefully and have good hearing you can tell if the
motor is binding at all, but many people do not.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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

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

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.

Specifically, how to figure that out is the question.

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've never tested one, but I put a drop of turbine oil on the
motor bearings every five years or so.

While that preventive work might be prudent, the sheer effort
to remove the entire dash simply to access the blower motor
would be problematic.

Still, if the problem is that the blower motor is merely using more
current as it gets older, why wouldn't a NEW FSU burn up within a
few weeks of insertion?

On 03/21/2013 06:04 PM, Bimmer Owner wrote:
Still, if the problem is that the blower motor is merely using more
current as it gets older, why wouldn't a NEW FSU burn up within a
few weeks of insertion?
If the unit is near its limits it might just get very hot and parts
start aging very fast - semiconductors will just fail after a little
while. The new unit should fail sooner than the old one but who knows
who soon, maybe after a few years. Peugeot's ( and Citroen) used just
one huge pnp darlington which failed quite often , it was working too
near its operating limits.

(just my 2 cents)
ismo

In article , jim beam wrote:

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure. Put a bigger transistor
in there.

unpotting is a nightmare - it will take much less time to build your own
pwm controller. who knows, maybe you can switch the existing unit???!!!

Unpotting is fun, it's a nice change in the day to just sit down for a couple
hours with a dremel tool and a dental pick.

But I agree, building an aftermarket controller replacement would not be
a tremendously difficult thing to do, and it might be a highly profitable
one.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bimmer Owner wrote:
On Thu, 21 Mar 2013 09:47:31 -0400, Scott Dorsey wrote:

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure.
Put a bigger transistor in there.

Here are pictures from the last half dozen who tried that approach:
http://www2.picturepush.com/photo/a/...g/12470740.jpg
http://www4.picturepush.com/photo/a/...g/12470742.jpg
http://www2.picturepush.com/photo/a/...g/12470745.jpg
http://www4.picturepush.com/photo/a/...g/12470747.jpg
http://www5.picturepush.com/photo/a/...g/12470748.jpg
http://www2.picturepush.com/photo/a/...g/12470750.jpg

These are kind of sloppy jobs. But it's clear there are two TO-3 devices
there which have been removed in all of those photos.

One problem with "put a bigger xtor" is that nobody on this planet
has produced a decent circuit diagram of the FSU.

Well, 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, so it's
almost certainly a custom, since it doesn't look like anything in their
standard book.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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.

I've never tested one, but I put a drop of turbine oil on the
motor bearings every five years or so.

While that preventive work might be prudent, the sheer effort
to remove the entire dash simply to access the blower motor
would be problematic.

Well, that's partly why I drive a 2002 and an E28, everything is much
easier to get to.

Still, if the problem is that the blower motor is merely using more
current as it gets older, why wouldn't a NEW FSU burn up within a
few weeks of insertion?

You would expect that, indeed.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"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

On Thu, 21 Mar 2013 16:59:01 -0400, tm wrote:

Just measure the battery current with and without the blower running.
Turn every thing else off.

That's a pretty good idea.

Of course, it's impossible to turn everything off, as the computer
won't go to sleep for 16 minutes after the car is shut and armed,
but, still - with the blower consuming something like 5 or 6 amps,
we should be able to measure at least that.

The problem, even with the car's additional electronics powered up,
is HOW MUCH of a difference are we expecting between an older blower
motor current draw and a new one?

Are we looking for a 1 amp difference, for example?

On Thu, 21 Mar 2013 16:00:13 +0000 (UTC), 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.

Specifically, how to figure that out is the question.

The simple answer is that they are under-designed for the conditions
under which they apparently are regularly subject to.

On Thu, 21 Mar 2013 15:22:42 +0000 (UTC), Bimmer Owner
wrote:

On Thu, 21 Mar 2013 03:55:47 -0700, the will wrote:

Blower motor drawing too much amperage taking it out.
Change the blower motor anytime?

This is an interesting approach, given that the vast majority of
bimmer owners do NOT replace the blower motor - they replace the FSU.

While the blower motor replacement procedure is a major PITA, one
'can' test the leads from the FSU harness connector pins #5 and #1
which are power and ground respectively to the blower motor.

Again, we don't have a circuit diagram, but it has been said that
the blower motor takes about 6 amps (variously, depending on the speed)
but it would take a test jig to test that in operation.

To my knowledge, nobody has created that test jig (although I know
of only one attempt, which failed):
http://www.bimmerfest.com/forums/sho...&highlight=fsu

It's easy enough to test the resistance of the blower motor though,
and those results have come out at about 0.4 to 0.6 ohms.

It would be expensive to change a blower motor on a whim, so, how
would YOU suggest the blower motor be tested in situ?


If one replaces one of these perhaps it would be advisable to put a
fuse in the blower motor lines (it sounds like those can be gotten to
easily unlike the motor itself). If it's being blown by intermittent
high current draws the fuse could protect the $100 FSU. Another
option would be, at least for those who can live without the highest
blower setting and who think excess current draw is the culprit, would
be to put a power resistor in the blower motor line to limit the
current a bit. On the cheap pedestrian cars I drive the whole speed
control is just a trio of power resistors placed in the air flow to
help cool them. If they burn out (which is rare) they can sometimes
be fixed with a pop rivet.

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).

On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:

If the failure is that the blower motor doesn't run at all, they are
probably failing open. If the failure is either that the blower motor
runs at maximum speed, or a fuse blows, then they are probably failing
shorted.

Actually, I was remiss in not stating that the blower motor generally
fails by acting weirdly, often said to "have a mind of its own", and,
most often by a parasitic current draw overnight that kills the battery.

If the failure is that the blower motor doesn't run at all, they are
probably failing open. *If the failure is either that the blower motor
runs at maximum speed, or a fuse blows, then they are probably failing
shorted.


i guess they call replacing a simple resistor with a bunch of
transistors.... "progress"

i'd replace the module with a bunch of power resistors and maybe a PTC
(self resetting) fuse

Mark


Mark

On Thu, 21 Mar 2013 15:16:46 -0400, Scott Dorsey wrote:

there are two TO-3 devices there which have been removed
in all of those photos.

I don't know what a "TO-3" device is, but nobody removed anything
in those photos other than the goop that covered the circuit board.

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

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, 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).

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.

"Bimmer Owner" wrote in message
...
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).


Are you sure it is not already a pulse width regulator? Those transistors
look like they are TO-220 packages, not TO-3.
PWM has been around longer than SMT parts.

Maybe it is transients from the motor that are causing the failures.

Another place you could measure the current is by putting an ammeter in
place of the blower motor fuse.


tm

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.

On Mar 21, 5:58*pm, Ashton Crusher wrote:
On Thu, 21 Mar 2013 16:00:13 +0000 (UTC), 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.

Specifically, how to figure that out is the question.

The simple answer is that they are under-designed for the conditions
under which they apparently are regularly subject to.

That isn't necessarily the case. For example,t hey could be correctly
designed, rated for the application, etc but have a manufacturing
defect in just one of the components.

A better questions is why BMW apparently doesn't give a damn
to do the failure analysis to find out what's wrong. I have a friend
who has an X5 and had this problem with the blower resistors.
Even worse, the only symptom was it was draining the battery
and it took a huge number of hours to track it down.

While you're all wondering about that problem, might as well
add the fancy aux radiator fan to the list. This car had that go
and now the replacement one has failed again. And the
symptom there is, again, it drains the battery even when the
car is off. That fan is a real POS. Instead of just a simple
fan motor, it's a fan that's variable speed, driven by a PWM
signal. So, instead of just a motor, that fan sitting in front
of the hot radiator has electronics in it. A real genius of a
design. And for what? Like the fan can't just be on or off?
Only reason I can think of is that they want to save a few
watts of power to try to get better fuel economy. And for
that their customers get to shell out $500 for a new fan
every few years.

On Mar 21, 8:08*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.

The dopes at BMW aren't any better at PWM's either.
They use a PWM signal to control the aux fan on the radiator.
You, know, the one that comes on if the cooling temp gets
too high or the AC is on, etc. Apparently just a simple on/off
motor wasn't good enough. So they made another one of
their German electronic miracle gadgets that's part of the
fan motor. That's right, electronics sitting right next to the
hot radiator.....

On the TV show All in The Family, the meathead was arguing
about Nixon and Watergate with Archie. Archie told the meathead
that Nixon's mistake was when it involved electronics, ie bugging,
taping, etc, that he should have used the Japanese, not Germans,
ie Haldeman, Ehrlichman, etc. I think Archie was on to something.

On Mar 20, 11:08*pm, Bimmer Owner wrote:
Does anyone have insight into what is the root cause (and repair) of the
FSU failure that plagues almost every 1997 to 2003 BMW?
*http://www.bimmerfest.com/forums/att...entid=126060&d...

Also, does anyone have an idea HOW TO TEST a "repaired" FSU?

The "blower motor resistor", which also goes by FSR (Final Stage Resistor)
or by FSU (Final Stage Unit), is known to fry itself in almost every single
E46 (3-series), E39 (5-series), and E38 (7-series) BMW.
*http://www.bimmerfest.com/forums/sho...d.php?t=143393

The problem with replacing this ~$100 part is that the new replacement FSU
fries itself just as often as the old one did, so you end up repeatedly
replacing your fried FSU every few years or so.
*http://www.bimmerfest.com/forums/sho...d.php?t=528566

That's fine for most people (although the DIY is a PITA) - but I ask
this newsgroup whether anyone has any insight into WHAT is actually
breaking - and - why?
*http://www.bimmerfest.com/forums/sho...d.php?t=309399

Here is the best (admittedly sketchy) wiring diagram we have so far:
*http://www1.picturepush.com/photo/a/...g/12467819.png

I had a dodge caravan that fried its heater AC motor speed control
resistor repeatedly....

the connector to the wiring harness detoriates from the high current
and the voltage drop causes the connector to heat up and the entire
assembly fails.

Oddly enough I repair roll laminators that apply plastic film to paper
think menus

laminators experience similiar failures so I did the following.

Purchased a new resistor block, soldered wires on all the connectors
putting a heavy wire on each one.... Put a pigtail on each one.
Installed resistor block. Its screwerd to the fire wall.

Cut the plug assembly off the harness, stripped all wires, twisted
them together and installed wire nuts on each one.

had the van for years with zero problems for this part

On 03/21/2013 12:05 PM, Scott Dorsey wrote:
In article , jim beam wrote:

I don't see why it is so hard to unpot one of these things and repair them
directly, especially if it's a semiconductor failure. Put a bigger transistor
in there.

unpotting is a nightmare - it will take much less time to build your own
pwm controller. who knows, maybe you can switch the existing unit???!!!

Unpotting is fun, it's a nice change in the day to just sit down for a couple
hours with a dremel tool and a dental pick.

i'd rather repair light bulbs.



But I agree, building an aftermarket controller replacement would not be
a tremendously difficult thing to do, and it might be a highly profitable
one.

well, it cost me about $18 in parts to retrofit the linear dash light
dimmer on my civic with a pre-built arduino unit. a custom unit could
come in substantially less than that, if in sufficient quantity.


--
fact check required

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.



Specifically, how to figure that out is the question.

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


--
fact check required

On 03/21/2013 06:01 PM, wrote:
On Mar 21, 5:58�pm, Ashton Crusher wrote:
On Thu, 21 Mar 2013 16:00:13 +0000 (UTC), 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.

Specifically, how to figure that out is the question.

The simple answer is that they are under-designed for the conditions
under which they apparently are regularly subject to.

That isn't necessarily the case. For example,t hey could be correctly
designed, rated for the application, etc but have a manufacturing
defect in just one of the components.

but that's not going to apply to multiple different unit manufacturers,
over long periods of time.



A better questions is why BMW apparently doesn't give a damn
to do the failure analysis to find out what's wrong.

um, because it's a profit center? either they charge you $100 for a $6
unit, or you get fed up with the vehicle and buy a new one. that latter
is the psychology of their target market.


I have a friend
who has an X5 and had this problem with the blower resistors.
Even worse, the only symptom was it was draining the battery
and it took a huge number of hours to track it down.

While you're all wondering about that problem, might as well
add the fancy aux radiator fan to the list. This car had that go
and now the replacement one has failed again. And the
symptom there is, again, it drains the battery even when the
car is off. That fan is a real POS. Instead of just a simple
fan motor, it's a fan that's variable speed, driven by a PWM
signal. So, instead of just a motor, that fan sitting in front
of the hot radiator has electronics in it. A real genius of a
design. And for what? Like the fan can't just be on or off?

indeed - a very good point. which begs the question, if they can pwm
the aux fan, wtf can't they do it with the blower fan???


Only reason I can think of is that they want to save a few
watts of power to try to get better fuel economy. And for
that their customers get to shell out $500 for a new fan
every few years.

bmw are designed, root and branch, to be expensive to maintain and own
after the warranty period. they spend a lot of money on r&d to achieve
that. and even more on advertising to convince their target that the
extra cost is justified for membership of the "ultimate marketing
tagline" club.


--
fact check required