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Old March 21st 13, 03:22 PM posted to rec.autos.tech,sci.electronics.repair,alt.autos.bmw,alt.home.repair
Bimmer Owner
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Posts: 58
Default Root cause insight into the common BMW blower motor resistorfailures

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?

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