Replacing the final stage unit/blower motor resistor (E39)

Not sure if anyone is aware about but...
1. The failure is usually caused by bad contanct of the soldering inside the FCU
2. Re-soldering resolves 80% of the FCU failures.
3. Simple and no cost. Not sure for how long it lasts but seem to be fine for loooong.
4. Basically re-solder those 9 legs after removing the insolation:
http://img87.imageshack.us/my.php?im...7000361xr6.jpg
Aftwrwards use plastic to close and isolate the FCU.
Instal it back and enjoy.

Apologies for the quality of my response, I am in a hurry and bit tired

Not sure I could do this one..........but thanks for sharing some useful information.

Thank you for this very informative write up. I changed the FSU today. Hopefully the problem I am having with the battery draining will go away. When the fan turns ON I noticed a louder noise than the original FSU. I don't know if it is normal or not. The fan turns OFF now as soon as I turn OFF the engine.

there is also a "cabin air fan" located in the center console behind the ventilation console.........it can be noisy as well (mine is).........but all it typically requires is a cleaning and drop of oil to reduce the noise.

Hi All! Just wanted to say thanks!
I cruised over on a link from the M5Board to this most useful thread and just finished changing out my FSU with a replacement from Pelican Parts. Couldn't (well wouldn't) have done it without the excellent guidance provided here.

All the best.

Phil

This is certainly one of the most helpful threads on the forum.................

Thank you Elvis530i for your help on this!! , Great steps, I just replaced the FSU on my 2002 X5, followed your steps and Voi-la the fan is working again. The whole process of reading this fourm and getting the part and install it, took me 1.5 hours.
The only obstical I had, the plug was very mean to un-plug, so I broke one side of it, but hey, it's still functional.
Cost was less than 100 CDN Dollar.

So - my newly (as of June 2011) replaced FSU may need replaced again soon...! Good thing I keep recipts...

Got in my car yesturday after a workout and as I slid my key into my ignition switch - I was shocked to hear the blower fan come on full force...I looked down and saw the "Max A/C" button's light was clearly on...and the key was still in the "Off" position! I even heistated and stared at it a minuite to insure my workout wasn't causing my mind to play tricks. Indeed it was real. I simply switched it off (and it immedialty turned off), re-checked the key position and then started the car normally. It was a chilly day, I have not used the A/C in any form for at least three weeks now. And I actually do not recall using the "Max A/C" switch more than 2 or 3 times in the year I've owned the car.

No issues since, pretty odd I have to admit...!

certainly one of the strangest stories yet..............does anyone else drive the car?

No - just me...I agree it's pretty strange.

I work in engineering and am used to "oddities" from components and systems (especially me myself) but it's strange to face them in my daily driver.

I was an Engineer myself before becoming disabled; still do most of my own work, just slower than I used to be.

30 minutes start to finish - great write up ! Thanks

happy for you......

Hello. I have a 2001 540i that stopped blowing a few months ago. After reading these instructions I was able to replace the FSU in about 20mins. and all has worked for about 60 days. Then I got in the car and before starting noticed it was already running. I started the car and none of the A/C buttons worked and none of the lights would light when pushed. It seems the entire A/C unit is out. When I start and drive the car, it only blows air from under (heater vents) and the air gets warmer as the engine warms up. So that the windows have to be down to bare the hot temp inside the car. I thought the FSU must have gone out again so I just replaced it with another new one but it is still performing the same way. It blows with the key out. I have to disconnect the battery to make it stop and when the battery is connected and the car started, the A/C section in the car does not respond to any of the buttons pushed...

Has anyone had any problems after replacing a new FSU?

check the basics first: fuses, wiring harnesses', settings on the vents (blue is cold, red is hot) etc..........do you think the instrument console could be bad? I don't think this is related to the FSU at all. Let me check my Haynes Manual..........

A code reader would help with diagnotics, but I don't feel this is a DIY project as there are so many factors "in play": Blower Motor, Heater Matrix, Sensors and Sending Units, Cables, etc...........think I would consider the dealer, or a qualified mechanic on this one. The Haynes Manual is "littered" with probable causes for your issue.

Thank you for looking. I guess I will have to, it just seems like the same symptoms as so many others that I was sure it had to be another bad FSU.

Thanks again...

I have been thru something similar to this myself, and ended replacing my FSU twice; but the fan I heard running the second time around was the Cabin Air fan (located inside the center control cluster). But I don't think this is what you are dealing with................hopefully it's just a sensor or a sending unit.

It does sound like the cabin air blowing. How did you repair that problem?

Thank you so much for the post with the great pictures on how to replace the part. The dealer wanted $700 to fix it. Thanks to your great post, it was only $70 and about 15 minutes of my time. Works great now!!!!

Can anyone who had a problem with the fan continuing to run when engine is off and key is out, tell me if your climate control unit did not function as it should? (no lights, fan speed lights, none of the buttons seem to control anything with the engine on or off) I have a 2001 540i that I just replaced the FSU 60 days ago, (Thanks to this site) and when I heard the fan running after I turned the engine off, I just assumed it was the FSU again and didn't notice the control unit. I replaced the FSU a second time and now realize that's not the problem. Since I can hear the fan running, I would assume the blower motor is ok? yes/no If so how many fuses and relays need to be checked and last, is there a way to test the climate control unit?

Or should I be checking something else?

Thanks again for your help.

$700 is the highest quote I have ever heard...........Way to Go!

This is definitely a great thread, however, I'm having a problem removing the plug! I've pinched, squeezed, wiggled that thing but it won't budge. Are there any other hidden tabs I might be missing? I certainly don't want to break anything, but it's driving me crazy.

Also, the replacement part won't get here until Tuesday of next week. Is it safe to drive the car w/the FSU unplugged but leaving the unit in its place?

Edit: Finally got it unplugged and, according to the SA at the dealership, it's ok to drive w/it unplugged. Now, just waiting for new part.

Like an old boss of mine used to say: "This is why they call it work."

The repair itself is just as simple as described in the excellent write-up. However, if you are above average in hand size you're in for a bit of a trial. The fit of the parts and the positioning of your hands required to release the clips for the first plug is extremely tight.

That said, I got the repair done reasonably quickly but not without sacrificing a little skin off my right thumb.