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

this is why they call it "work" my friend; some experience with Yoga would help!

Today, someone asked what's the difference between the FSR and the FSR and the blower motor resistor ... and I pointed him here (after explaining they were the same thing).
- E39 (1997 - 2003) > FSU vs FSR difference and symptoms?

Just for the record, this is the canonical thread for E39 FSU/FSR/Blower Motor Resistor problems ...

In addition, these from the bestlinks should also be of benefit to users:
- What is the canonical thread on the BMW E39 FSU/FSR/Blower Motor Resistor (1) and what is the right brand FSR to purchase (1) (2) when your interior heating & air conditioning HVAC/IHKA blower motor goes haywire (1) (2) (3) (4) (5) (6) (7) (8) & how to repair your own final stage resistor including an autopsy & wiring diagram schematic (1) (2) and why a bad final stage unit will cause the battery to drain overnight (1) (2) (3) & how to isolate and replace the E39 blower motor (1) (2) (3) (4) (5) & how not to replace the FSU (1)

I appreicate all of your hard work: you help all of us, and I appreciate you very much.

April 2006 and here we are May 2011 and your original post is still helping lots and lots of people - including me!

On Sunday afternoon I came home and the cooling fan wouldn't stop. First time it's done that. I had to leave it running while I checked the web and found your excellent post. I decided to get the part next day and try to do the fix as described.

Later in the evening the fan had stopped but only because the battery had drained. Then I realised I was locked out of the car because central locking / unlocking also stopped. Luckily I was still able to open the boot, attached a battery booster then got back in! I left the car unlocked with the boot slightly open all night, just in case!

Today I visited the dealership and lo and behold they had the new part (£80) which I bought and it sat on my desk all day. This evening I had a go at the replacement. It's VERY awkward getting to the unit but I managed. Got the old one out and the new one in. Linked up to another car, waited a while, fired her up, and Bingo! Car started and No Fan Noise!! It worked!

So I just want to thank Elvis530i for a great post and if I could I would propose your post for the most useful post there has ever been!

Cheers, Richard

Cheers to everyone who offers help on this forum!

@Rich325 I concur. May 2011 and this 2006 post is super helpful. I just replaced my first FSU in about 20 minutes after receiving the part. My 2001 540i is making me more bold with repairs, got nothing to lose and there have been electrical bugaboos. Dealer told me the part would cost $186.00 AutohausAZ recommended by this thread had it for $52.00. The link from @bluebee about how not to replace the FSU Harness Connector was also helpful, I had wondered why I couldn't wiggle the thing off. Thanks all.

bluebee is the "go-to" guy for most anything!

bluebee is the "go-to" guy for most anything...........

bluebee is the "go-to" guy for most anything BMW.........

sorry to be redundant..........it's my medication-fried brain at work again!

I'll comment like all the others - very well written and helpful - I used it Saturday to swap out this FSU, only thing I would have mentioend at all different was to yank out the black insulating pad under the glovebox on the two white clips. After figuring that out, the job went well.

The symptoms mine possesed (yes, it was possesed) were of a running on fan and sometimes strange up/down/random speed. More important, it was draing down the battery in 3 days, then 1 day then overnight. Even speaking with the dealer folks while buying the part, they seemed to think it was the FSU. Mine cost $140 for the part, but it oculd have been worse, my local dealer is $120 initial for "diagnosis" and out local indy shop is around $99 for diagnosis as well. You took care of this.

Even double checked with an "arc test" on the battery negative post - much smaller sparks (just some draw from the two trunk lights) once the old FSU was disconnected.

Great work!

My 2001 530i (164,000 original miles) has had the mysterious blower resistor problem for years. I simply chose to ignore it. The fan would start up and run at all sorts of different times. Finally, the battery died in. Like a fool, I changed the battery myself (an Interstate one – not a BMW one) and realized that the fan was running all the time, even after I had switched the engine off. Debating whether to resign myself to the dealers $300+ gouging, I did a google search and found Elvis’ excellent post of 2006. I got the faulty part out in 30 minutes. I ordered the replacement part through Bimmerfest for $70. I put the part in when it arrived. I am now good as new. Thanks Elvis530i. Wish I had read the post before. Like many of the other grateful BMW owners, your post is helping all of us and it is 2011.

The problem was described as it happened, my blower was random and now it quit. I just ordered this part for $38 shipped on EBAY! SWEET! I cant wait for the cold air again.
it was hell removing the plug so i used pliers and it was easy!

Thanks for this very informative forum. I love this site. I replaced my FSU last fall because the blower fan was not shuting off. The problem seemed to be fixed, until yesterday when I used my AC. The blower fan would not turn off even after I shut the car off. Could the problem be the FSU again? I was thinking maybe it went out because I bought an after market one. Should I go out and but another unit or is there something that is happening to my car to make this unit keep going out. Kinda at a loss here. Any help would be great.

Thanks
Brandy

I knew I could count on this forum for yet another DIY fix.

Thanks guys! This really is an easy fix. Some of the black insulation stuff that is around the box chipped off and fell to the floor. Is that going to be a problem? The A/C felt like it was blowing harder than before after the fix. It was over 90 degrees out today so I am very happy I was able to fix this. The local parts place I use had the OEM part for $117. I found an aftermarket version for $35 from a local Ebay Seller and it works just fine. This is the cheapest repair to date for me and I am sure it saved a ton of money over taking it in.

This info on diy replacement of the blower resistor was so excellent that I had to create a user account just to log on to tell anyone who might follow me just how helpful these directions were. Just excellent, answered questions and explained all of the thing that you would wonder about.

This site is full of tons of information. Not only how to fix and replace things, but how to diagnose common problems. There is not one thing that I have researched here that did not lead me to successfully repair the issue.

Elvis 530i - thanks for the post. My AC was possessed and wouldn't stop running even after I turned the car off. I saw your post and then disconnected the resistor as you said. That saved my battery over the weekend when no one was open to help me out. On Monday, I found a replacement part, installed it, and am now good to go. Your post saved me a battery and certainly saved me whatever a mechanic was going to charge me to diagnose and fix the problem.

Really appreciate it.

It's been said before, but thanks for the writeup. $52 part, 15min swap, full blower power for summer in NV. Should have done this last summer! BTW, this fix is not only for squirrely fans but also for those that just don't blow hard enough.

Bob

what up guys looks like everyones had luck with replacing the FSU unit except for me


I have a 2001 530i, battery doesn't drain... I hear a fan still running when I turn off the car, inside the car, I am not able to control the speed of fan and temp no matter what settings I adjust it to, when I turn on the AC button the fan goes at max speed.

Bought FSU from Autohaus for $52.09 "Behr" brand...
Installed and replaced factory unit. Fitment was fine, but symptoms were exactly the same.

Nothing was fixed

any ideas?

Based on your symptoms, the FSU swap should have taken care of it. Before calling Autohaus to discuss the posibility of a bad part, I'd be tempted to "reboot" the whole system by interrupting power from the battery for a couple of minutes. Also, I'd be back in there making sure that the plug was clean and seated properly.

Originally Posted by Mulepick

Based on your symptoms, the FSU swap should have taken care of it. Before calling Autohaus to discuss the posibility of a bad part, I'd be tempted to "reboot" the whole system by interrupting power from the battery for a couple of minutes. Also, I'd be back in there making sure that the plug was clean and seated properly.

I rechecked the plug and fitment today, it was a clean install. I'm not sure about rebooting the whole system is that a good idea?

Should I check for any fuses in the heater system? hmm

Elvis, this is a fantastic writeup and saved me money and grief. I have a couple of comments:

1. BLOWER STOPS WORKING COMPLETELY. This repair also works in at least some cases when the blower STOPS WORKING ALTOGETHER. A lot of the web-based commentary seems to imply that the FSU replacement only fixes blowers that are intermittent, or that have speed problems. In my case, the blower stopped working at EVERY SPEED. It was just like it was switched off. I followed all the commentary and tested it at all speeds -- NOTHING!! I was really afraid then, that the blower motor was kaput, and not the FSU, based on all the comments. But I decided to try the FSU first, and I'm glad I did. For $52 bucks, free shipping from autohausaz, it was really worth a try.

2. CONTORTION. For me to do this repair, I had to lower the passenger seat down as low as it would go, and move it as far back as possible, into an almost bed-like position. Then I climbed into the seat backwards, with my feet toward the back of the car, my body upside down, so I could get my head and arms underneath the dash, facing up towards the FSU. It's very close in there, but even a monstrously large person like myself (6'2", 280 lbs) managed to get in there with some difficulty. If you have a small, thin person in your family who is very flexible, you may want to engage them for the removal and installation of the FSU.

3. FUSES. Of course, the first thought is to check the fuses. Once the "easy" ones in the glovebox are checked and found to be ok, the thought is that Fuse 75 or 76 might be to blame. They are big 50 amp fuses that are located in a very difficult place, behind the glovebox. I know there is a lot of commentary out there about how to remove them. But REPLACING them is something else altogether. No one mentions that there is an aluminum brace that is in the way. After diddling around for a long time, I found that the only way to REPLACE those fuses is to jam your hand in back of the aluminum brace by force, and punch the fuses in from the top. The aluminum brace will move enough to let you get your big fat hand back in there if you use force. Of course, in my case, all of this was wasted, since the fuse was not the problem. However, to get to the FSU, it really helps to have the glovebox out of the way anyway, so all the effort was not wasted.

4. FSU REPLACEMENT. Make a mental note of the orientation of the FSU as you take it out. There is little space to work down there, and it is very difficult to keep turning the new one around trying to fit it back in. Plus the new one is not exactly the same shape as the old one. I printed out a picture of the FSU in place from Elvis' DIY and brought it with me out to the car. That really helped. Nevertheless, be prepared for some jockeying to get the old FSU out, and the new FSU in -- the only thing that I was concerned about was damaging the very soft prongs in the new one while installing. Luckily that turned out to be not a problem.

5. SOFT PRONGS. I should note that the new part, from BEHR (the old one was made by VALEO) had very soft prongs. The old one's prongs were very hard and could not be bent, but the new ones were very bendable. In fact, I thnk I accidentally bent them a little while fooling with it. I did not know whether this made a difference, but where they touched each other, I bent them back so that they did not touch, and were aligned in neat rows. Maybe this made no difference, but I didn't want to take the chance.

In my case, as soon as I replaced the FSU, everything went back to normal! It's like magic. I was dreading having to disassemble half the car and replace the blower motor -- but that won't be necessary, thanks to our friend Elvis! Really appreciate what you have done here for all of us.

--Ron

In need of advice. I've had the same problem as repeatedly described in this post. No blower, all else looks fine, replace FSU, still no blower. I've jumped the FSU wires as described here(or elsewhere) and the motor is fine. Fuse is good. FSU plugged in (old or new), no blower. I've read somewhere that I should have ~3 to ~8 volts when testing voltage between two wires at the FSU connector while changing the fan speed on the digital panel. My meter reads .01 volts and only changes to .02 briefly with key on/off changes, not when hitting the button to change fan speeds. Does that mean the climate control panel is bad? Are there more tests I can do on the panel? Are there more tests to perform on the FSU? I've tested ohms between aluminum posts and pins on the FSU both old and new read nothing on all but one pin. Is it possible that the new FSU is bad? Any and all helps is greatly appreciated. FYI new FSU is very similar to old one. The car is new to me and I think it may have been replaced once before. I bought my new one through Bav.