Blower motor (3rd time) E39 2002 530D Touring

[Bookerfatz]

There seems to be more threads about malfunctioning blowers/FSU units then any other. In the past 2 years I've replaced twice both my fan and FSU units each time in July. Yet again my blower has been running at varies speed, can't seem to make up it's mind etc. It always shuts off though when I turn off the car which I understand is common indicator (not stopping that is) for a malfunctioning FSU. It's quite frustrating to say the least and that's not to mention expensive. I can replace the FSU yet again but that's about the limit of my mechanical capabilities. I suspect that it might not ever solve the problem as it didn't the past 2 times either. For the life of me though I can't suss out my particular problem. I love the car though (260,000km) and hate to let her go. I need this fan to work not only for winter but it's really hot out there.

[MIKYZZ4]

My question to you, that may clear this up is:
What type of replacement parts are you using,
Genuine BMW replacements,
or cheap imitation Chinese knockoffs?
Remember this, the original BMW part was installed in 2002,
and lasted many years before it failed, and you installed a replacement.

[Bookerfatz]

Thanks for the reply. I bought the last FSU at a BMW dealer. Now whether that was an official part or not I don't know. It did work for exactly one year. You're absolutely correct though to offer up the question. I would wish the solution was so simple.

[MIKYZZ4]

Thank you for verifying the part quality,
now to focus on other possible causes.

What part# is being given to you by this dealership?
Is this the one:https://www.fcpeuro.com/products/bmw...204b-1#fitment

[Bookerfatz]

I can't answer that question actually. It was a year ago that I bought it and I was in Italy and we drove directly to the BMW dealer in Padova to buy the item. I have no idea what the part number was not do I have the box it came in. (BTW I live in France but travel extensively if case you were wondering).

One point that seems clear though is that the erratic behaviour 'seems' to be triggered by extended A/C usage. The first time was the same time of year and last year was in July. That being said, I've owned the car about 8 years total so there was a good 6 years of no fan issue. I've not idea of the car's history before I bought but I think it was a one owner vehicle.

[Bookerfatz]

BTW- I can verify that the part number you sent for FSU also corresponds to my car.

[MIKYZZ4]

I suspect low quality parts after BMW original failure, or faulty installation.
Maybe part overheating due to lack of air circulation? Moisture? Corroded connections?

[Bookerfatz]

Well, all possibilities of course and good points to consider. The obvious and least expensive choice then would be to go to BMW dealer here, buy new FSU and then swap out the old with the new. Seems reasonable given the alternatives. I certainly will be sure to verify new part number as well and not settle for anything but the real thing. Seem logical to you?

[MIKYZZ4]

Very logical, I like your thinking, lol.

Btw,in the States Genuine BMW replacement parts come with 2yr warranty,
or lifetime replacement warranty from the FCP link I provided.
I understand you're in France, so I am not familiar with warranties available to you.

[MIKYZZ4]

The real thing:

[Bookerfatz]

Hmmm.. warranties will check out. Isn't FSU considered an electronic part though? Maybe not though... it's mechanical right? Anyway... will to the dealer tomorrow and see what they've got. Will post a follow up after. Thanks for your patience here with me your help. Certainly having a hand to hold and being able to talk with someone more knowledgeable is huge. Operating in the dark is not fun and can be costly. This forum is priceless. Thank you very much!

[MIKYZZ4]

Glad I am able to help a fellow BMW owner in need of assistance.

[Bookerfatz]

Got the part installed today NP. Took about 30 minutes. Turns out the FSU that was in there was indeed an official BMW unit. Hmmm... Well, as I said, this is my third time. Fans blowing steady now but I've got about 4000km over the next 2 weeks and that will certainly be a test. It's hot and steamy over here too so it will be good to have a working A/C. I did note that those 'prongs' actually extend into the chamber below the main blower. I assume those prongs are to release build up heat from the FSU itself. There was no sign of moisture, dirt or anything actually from the unit I took out. I wonder if there is any kind of venting going on in that little space beneath the blower? Activated by a sensor? There is a "Evaporator Temperature Sensor) I see on the parts diagram <https://www.realoem.com/bmw/enUS/showparts?id=DP71-EUR-01-2002-E39-BMW-530d&diagId=64_1029> #04. Would you know anything about that or what it does. Couldn't find anything online in regards this. Anyway, I guess that's it for now. Hopefully this will be last of this problem.

[MIKYZZ4]

As long as that lower chamber is free of debris, there should be no issues.

The Evap Temp Sensor is part of the AC system.

Yes,hopefully that new FSU solved your problem.

[BarryM]

I’ve replaced my FSU twice in 6 years and the main blower fan last year after it had been squealing for months and then died. Lots of threads about failed FSUs and I think it’s just luck of the draw so fingers crossed you’ll be lucky this time.


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[f355spider]

I’ve replaced my FSU twice in 6 years and the main blower fan last year after it had been squealing for months and then died. Lots of threads about failed FSUs and I think it’s just luck of the draw so fingers crossed you’ll be lucky this time.


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Very possibly. My story: 2001 540 with one FSU replacement in 2002 under warranty. I had a failure around 2006 and went to the BMW dealer and purchased a new FSU, that was of the last updated part number (there were several updated part numbers but BMW settled on a final one around 2005 or 2006). 2017 I had problems with the blower motor and figured I would start with the FSU and bought on oem replacement from FCP Euro with the lifetime warranty. No improvement, so I had the blower motor replaced with a new oem Valeo replacement. All good...BUT, a year later that "new" FSU failed (symptom was blower cycling on and off after shutting off engine, draining battery)...fortunately I had the FCP Euro warranty to back me up, so I ordered another, and swapped it out, returned the old one for credit back to my credit card. So my point is I wish I kept my old FSU that was working fine...

[Bookerfatz]

Update: 3 weeks later and 5000+ km added on, my blower is working just fine (so far). The newly installed FSU seemed to do the trick. Some other problems cropped up but I will start a new post for that. Thanks again for your help.

[geargrinder]

I believe that there is a sneaky number of undiagnosed FSU poor connections out there, that get 'fixed' mainly because a new FSU gets tossed in there which refreshes the connection.

I also went through the multiple FSU dance. Dealer non-dealer, "known good used" all kinda FSU's. FSU's out the butthole. I prob have 2-3 lying around dammit. Might have thrown out good ones even!

At one point I lightly tightened up the pins on the connector with a pick and that was good for a long time...

Then started symptoms again last winter. I'd already tried solventy-contact-cleaner on the pins but this time I used a schmear of dielectric grease just for the hell of it. Problem immediately went away and its been 100% fine ever since.

My working theory is this is due to aging on the surface of the pins/socket, and/or, because the pins start to 'creep' under temp changes (all that stuff gets nice and hot...) stray resistance gets added to the resistance in the circuits causing improper voltage drops, perhaps on the control signal line even moreso than the supply lines. If I am correct, then it really only applies if your symptom is indeed "runs at weird speeds, like either less than its supposed to, or, ONLY if you turn it up to max"... (which I have seen... really irritating to have to constantly override it to "MAX" to get any fan at all...) So, if your symptom is "never runs even after reseating the connector"... or... "runs even when car turned off", then the FSU indeed is bad. But otherwise, might try this - it only takes 5 minutes and a few bucks to get a tube of dielectric goo. The (again: working theory) reason contact cleaner wouldn't work as well is because it evaps eventually and then when the pins warp and move around and 'stick' again, while the grease stays in there and lets thing slip around and stay connected.

[Bookerfatz]

That's pretty good deduction Geargrinder. At some point it's like "why not try this" right? I'm at that point where I mistrust the thing all the time if you know what I mean. Just waiting for the fan to start acting up again. I'll remember what you wrote for next time. One question though to be sure I know exactly what you're talking about when you say "pins"... this would be where the FSU plugs into the wires right? I can only think it would be that but just to be sure... Thanks for posting too!

- - - Updated - - -

[geargrinder]

Yes the electrical connector. I smeared a light dab of dieletric grease on the top of the electrical pins (NOT the cooling spines!) then same on the connector sockets (be careful not to over-goo those)

[Bookerfatz]

I thought as much but just to be sure. Thanks much.