DIYbanter - View Single Post - Root cause insight into the common BMW blower motor resistorfailures

jim beam

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