DIY: FSU (aka Blower Motor Resistor) replacement pictorial guide

Starless · Jul 25, 2010

It was my turn to replace the FSU (blower motor resistor). I just got tired of the pulsating pattern of the blower and its shutting off on its own accord. It is especially frustrating in the 100F degrees St. Louis weather. I ordered the part through one of my favorite sites: www.eeuroparts.com that has great prices and both OE and aftermarket parts. The FSU is made by Behr (OEM). The cost was $59.99 shipped. It took an hour to install and it was a pain in the neck (literally) due to its location under the dash. If you have problems with your back/neck/shoulders I'd recommend to delegate this repair to a shop technician (hopefully without these problems). You have to spend some time in the area below the glove box on your back and side with your legs on the passenger seat. There is simply no other way.

The DIY is in the pictures. Sorry if I missed something. But that's just pretty much the way I did it. I'll just mention it here one more time that I did not find it necessary to remove the air duct and control motor to get to the resistor like some other diys suggest. Of course it will make things a little easier but will take more time. And I did not want to spend more time on the 95F degrees evening sweating in the footwell of the car. So here is the pictorial guide:

Solidjake · Jul 25, 2010

Very nice as always. Thanks.

mawana · Jul 25, 2010

Very clear and cleanly done! I will definitely come back to this when it's time.

marinekilz · Jul 25, 2010

:thumbup: Very nice work, enjoy all your constant cool air this summer

Ryans323i · Jul 25, 2010

Thank you! And bookmarked!

P_T · Jul 25, 2010

I vote for a new title of Chief DIY Illustration Guru.

Great job as always...thank you.

Starless · Jul 25, 2010

Haha, I just like to take pictures of my repairs when they come up

Thanks everybody for comments. I'll need to include some other good FSU links for those who decide to remove the air duct. It's a couple of extra steps from what I've read.

C-Bear · Jul 25, 2010

To the wiki we go?

Starless · Jul 25, 2010

I'll link it there later

Thanks!

New FSU definitely solved the pulsating/interrupted air stream problem. Cause it started getting annoying...A lot of maintenance still ahead...

maviduya · Jul 25, 2010

starless,

i've replaced the fuse for the blower motor three times today and the only DIY that i did was to disconnect the power window motor on the front passenger side. i've checked all the wires in that door and none are exposed.

i'd like to confirm that a faulty blower resistor pack (aka FSU) would lead to multiple blown fuses...

more background material: the lights on the IHKA panel turn on with the key in the pre-ignition position...just no air from the vents...

thank you in advance!

mark @ san antonio

Starless · Jul 25, 2010

maviduya said:
starless,

i've replaced the fuse for the blower motor three times today and the only DIY that i did was to disconnect the power window motor on the front passenger side. i've checked all the wires in that door and none are exposed.

i'd like to confirm that a faulty blower resistor pack (aka FSU) would lead to multiple blown fuses...

more background material: the lights on the IHKA panel turn on with the key in the pre-ignition position...just no air from the vents...
thank you in advance!

mark @ san antonio

Not sure about fuses, mine never blew...
The IHKA lights working and no air is definitely the FSU. Is it only with the key in pre ignition? What about when the car is running?

akhbhaat · Jul 25, 2010

I performed this job in my old 323i, and this is really a top shelf DIY. The photos and description are excellent. Nice work.

Hopefully, you won't have to worry about this again. The FSU design was revised twice, I believe. All I can tell you is that my 2005 got the newest version of the part from the factory and has not once had FSU issues even at 5.5 yrs/62k miles, whereas my 323i had it twice in 7 years/75k miles (first at 2.75 years/20k miles, second at 7 years/75k miles). I do believe the part installed during the first repair was the same as the original, because I don't think it had yet been revised even once at that point.

jcatral14 · Jul 26, 2010

Thanks for taking the time to put this together Alex. Excellent DIY :thumbup:

akhbhaat said:
...2005 got the newest version of the part from the factory and has not once had FSU issues even at 5.5 yrs/62k miles...

Great news

maviduya · Jul 25, 2010

both...

starless,

you asked: "Is it only with the key in pre ignition? What about when the car is running?"

answer: BOTH...the fuse blows when i turn on the A/C in pre-ignition AND when i turn on the A/C when the engine is running.

thanks!

mark

Starless · Jul 26, 2010

Is it fuse 28?

maviduya said:
starless,

you asked: "Is it only with the key in pre ignition? What about when the car is running?"

answer: BOTH...the fuse blows when i turn on the A/C in pre-ignition AND when i turn on the A/C when the engine is running.

thanks!

mark

Mark, there is a BMW TSB concerning your problem. Here is the link:

http://www.bmwtis.com/tsb/bulletins/bulletin_graphic_temp/B641005g.htm

So, I'd research the "e-box fan" version discussed in the document.

Also, read these threads on e46F:

http://forum.e46fanatics.com/search.php?searchid=15113165

One guy in the thread below claims that FSU solved his blown fuse problem:

http://forum.e46fanatics.com/showthread.php?t=687597

Keep us updated!

EDIT: In TSB I believe they are talking about part # 5 in this diagram:

http://www.realoem.com/bmw/showparts.do?model=ET37&mospid=47720&btnr=12_0899&hg=12&fg=35&hl=3

Part #5 cover with blower. There are 2 part #s, one for manual , second for autos.

And IF this is indeed the cause of the short, then this thread has instructions how to change the "e-box fan"

http://forum.e46fanatics.com/showthread.php?t=291383

maviduya · Jul 26, 2010

stupid mistake...

starless,

i discovered the reason for my problem...remember how i said that i worked on the passenger power window? the fuses that control window lift are #48 and #49. the fuse that kept blowing was #50.

#49 is supposed to have a 5 amp fuse and #50 a 40 amp fuse...

here's what happened: when finishing up with the DIY on the window, i transposed the fuses...i put the 5 amp fuse in #50 and the 40 amp fuse in #49.

i discovered this when, as a last-ditch effort before ordering the resistor pack, i checked each and every fuse for correct amperage.

THANK YOU for sticking this out with me and for answering my questions...

naturally, i feel really dumb...next time, i'll be more careful...

mark @ san antonio

Alex Phillips · Jul 26, 2010

Starless,

I have had a problem with the AC/Heater air flow being inconsistent when the fan speed is in the middle range (not low and not high). The AC airflow seems to be like a rollercoaster almost shutting off and then revving up a little when in the middle range.

Could this be the blower motor resistor? If it is, I'd like to DIY. Your instruction guide looks very good. My car has almost 90k and is 8 years old.

Starless · Jul 26, 2010

Alex Phillips said:
Starless,

I have had a problem with the AC/Heater air flow being inconsistent when the fan speed is in the middle range (not low and not high). The AC airflow seems to be like a rollercoaster almost shutting off and then revving up a little when in the middle range.

Could this be the blower motor resistor? If it is, I'd like to DIY. Your instruction guide looks very good. My car has almost 90k and is 8 years old.

Alex, yes, this is your blower motor resistor for sure. Classical symptoms. Let me know if you have any questions how to diy.

Alex Phillips · Jul 26, 2010

Thanks Alex. Other than a t-20 screwdriver, I should be good to go. Thanks for the DIY guide. I am going to give this a shot probably this weekend.

chodan1 · Jul 29, 2010

excellent pictorial guide

Hi there, just wanted to drop a note thanking you for the intructions and pictures to replace the blower resistor. I wasn't sure I wanted to do this myself but your pictures gave me the courage to do it. I just replace mine for a 2002 325i. I payed $127 for the part and 2 hours of work. For those out there who is looking for tips, you need a good light b/c it is pretty dark in that area. There is not alot of room to fit your body to work on this so I pushed the chair back, sat reverse on the chair and slid myself down under the glove box. I did my in two stages with a 1/2 break in between, 1. teardown until I am able to see the FSU. 2. Remove and install.

Starless · Jul 30, 2010

chodan1 said:
Hi there, just wanted to drop a note thanking you for the intructions and pictures to replace the blower resistor. I wasn't sure I wanted to do this myself but your pictures gave me the courage to do it. I just replace mine for a 2002 325i. I payed $127 for the part and 2 hours of work. For those out there who is looking for tips, you need a good light b/c it is pretty dark in that area. There is not alot of room to fit your body to work on this so I pushed the chair back, sat reverse on the chair and slid myself down under the glove box. I did my in two stages with a 1/2 break in between, 1. teardown until I am able to see the FSU. 2. Remove and install.

Congrats! Good tips. The only thing is - $127?:yikes:From dealership that must be? My price was $59...

chodan1 · Jul 30, 2010

The best price I saw online was $76 + at least $20 shipping since I needed it fast, so I got it from the dealer.

Alex Phillips · Jul 30, 2010

Chodan - eEurope Parts had it for around $59 with shipping included (FedEx) which was like a 2-3 day turnaround. I got it from there and plan to try this job later today or tomorrow.

Alex - I am giving this a shot and thanks for the assistance/DIY details above. I'll let you know how it goes.

chodan1 · Jul 30, 2010

When I was searching online, this parts store never came up

, I do see it now and you are right, this is actually the same part ( brand) I installed and payed $127. Now I know!

conrad721 · Jul 31, 2010

i think my blower resistor needs replacement too.

the air shuts off even with the a/c compressor is running.
playing with the fan speed doesnt do anything.
i did a "reset" by placing the ignition key all the way to pos 2 and then back, and somehow it finally worked.
this happened twice already.
im afraid time will come that the blower might not even work anymore.

with the heat and humidity here in my place, driving without the air conditioning will literally melt me.

thanks to starless for the DIY.

TDS1 · Aug 7, 2010

My story - The climate control in my 2000 328i started acting up about 3 weeks ago. As any of you know that it has happened to, it is extremely annoying especially in the middle of summer. A brief google search confirmed that blower motor resistor was indeed the problem. I read some of the DIYs on how to replace it, but I am really bad at these sorts of things, so I didn't think I could handle the repair. It seems that in a 5 series this is a much easier procedure. So I contacted some local places to inquire about replacement cost. An independant BMW mechanic wanted $260 to do the repair, and dealer wanted $400+. So, was about to schedule an appointment when I found this thread. The pictures are so much clearer than the other DIY that I found, and it inspired me to give it a try. Ordered the part from Eeuroparts as OP suggested. Part arrived in 2-3 days. Figured I would get started tonight and see how far I could get. Bottom line - I was able to complete the entire repair in about 45 minutes. THANK YOU OP!!! Again, if I can do it, it can be done by almost anyone. The 2 parts I had a bit of trouble with were 1) Removing the floorboard trim piece - hard to get the final clip off - had to push really hard 2) Getting the FSU out of the socket - it was really hard to get it unclipped, but once I did I was able to wiggle it out - it was much easier to get the new one in.

A few of my own thoughts:
1) My FSU did have 2 screws in it, despite many reports that the factory doesn't put the screws in. Odd, but it wasn't hard to remove them.
2) A magnetized T20 definitely helps
3) I was able to kneel on the ground outside the car looking in to do the replacement - didn't seem too hard to do it that way
4) My best tip - I used an adjustable headlight to see what I was doing rather than a flashlight. It made it really easy to see what I was doing.

Many thanks OP!

bluebee · Aug 7, 2010

FWIW, we've been trying to find which FSR 'brands' are the reliable ones over in this FSR/FSU autopsy thread in the E39 forums ...

So far, we "think" the only reliable FSR is Sitronic/Bosch ... but time will tell of the others ...
Recommended:
- Sitronic/Bosch

Not recommended:
- GKR
- Behr
- Valeo,
- Siemens

Certainly not recommended:
- Meyle
- Hella
- Uro
- Denso
- Power Pro

Let's all pitch in to report the bad ones (e.g., GKR), so we can understand the good ones.

Starless · Aug 7, 2010

^ I'm not sure all this applies to E46. BMW FSU part numbers lead to 2 brands - Behr and Meyle. The part has been updated many times and the final version of Behr (0365 part number) seems to be problem free.

bluebee · Aug 8, 2010

FWIW, I understand. The electronics may be different. However, the symptoms are the same, the solution is the same, and even the brands are the same ... so I'll wager there's more similarity than differences.

So far, we're staying away from anything with GKR stamped on it, either in the metal or on the sticker. If it says Behr, you have to be careful as it also says GKR and BMW. Some even have FOUR brands listed.

So, it's confusing at best - but that's why we're all working together to identify which FSR brands to avoid in that thread where we took 'em apart.

cesmoot · Aug 16, 2010

It took me 4 hours (including going to get the replacement part) and a lot of frustrating moments and feelings of claustrophobia, but with my wife's help (her hands were small enough to push back the clip and remove the FSU (blower motor resistor).

Then we were off to BMW for the part: $134.00 ( I didn't want to wait to fix it)
The reassembly was a little tricky and only took about 1/2 hour and we were off to the car wash.

I did manage to break both the clips off the SDU harness, so be careful not to remove the harness until the FSU is out. Even with the broken clips the unit connected snugly.

Also, it was tricky getting the heater duct out (I do not see how you can do this job otherwise) and back in, but take your time you will figure it out. Pull back gently on the leather trim till it pops loud, but no more. You will not do any damage you can see. You have to work the heater duct out from the back to the front (use a light to see).

Drink lots of water and take several breaks. Once you do this once it will be a piece of cake the next time. I was moving nicely until I had to deal with the heater duct removal. Take your time here....

It helps if someone can hold a flashlight and hand you tools as you go. You will be working in a very tight space, so be prepared. My feet were dangling over the reclined front seat and out of the open back passenger door.

Thanks everyone for the threads. I couldn't have attempted this without you.

ElRosbo · Aug 17, 2010

Other Tools to Make This Job Easier

I strongly recommend anyone replacing the FSU on an E46 buy the following:

Craftsman Specialty Tool Set 4717

http://www.sears.com/shc/s/p_10153_12605_00904717000P?prdNo=13

That set contains a magnet on an telescoping handle that is perfect for removing the 4 Torx screws so they don't drop into a black hole, never to return. The kit also includes a Phillips/Torx screw starter that made reinstalling the Torx screws a breeze. I also used the bent end of the scriber to help me release the clips on the FSU wire harness plug (although maybe I could have released the plug easier after sliding the FSU out).

If you don't already have Torx screwdrivers, Craftsman has an inexpensive set for about $10 but I recommend that you instead buy their better quality drivers.

http://www.craftsman.com/shc/s/p_10...302000P?vName=Tools+&+Equipment&keyword=torx+set&prdNo=5&blockNo=5&blockType=L5

The handle gives a much better grip and the shank is much longer, which also was a help on this job. You can buy the set of 5 drivers for about $35 or just the T20 for about $7.

cesmoot · Aug 17, 2010

Vents blowing cold air (drivers side) and warrm air on the passenger side

After all the work I did yesterday replacing the FSU, I am frustrated today....the vents on the right drivers side are blowing cold air, the vents on passenger side are blowing warm air...did I do something wrong? Did I disconnect or not reconnect something? Please advise....

Starless · Aug 18, 2010

cesmoot said:
After all the work I did yesterday replacing the FSU, I am frustrated today....the vents on the right drivers side are blowing cold air, the vents on passenger side are blowing warm air...did I do something wrong? Did I disconnect or not reconnect something? Please advise....

You did nothing wrong. It's a classical bmw symptom of low/leaking AC refrigerant. I'd go to an indy shop and have them evacuate the system and refill it with the correct amount of refrigerant. In many cases just this solves the problem but if you have a persistent leak then it will need to get fixed too. Keep us updated.

cesmoot · Aug 18, 2010

Boy am I relieved

Alex, I called BMW; they were kind enough to give me the shop foreman after hours. He said I should add freon first. Went to Auto Zone and purchased the can with the gauge etc for about 27.00.

The gauge read in the blue zone, but I added more till it was just shy of the yellow area. What do you know...I drove the car home and noticed that the air was getting colder on the passenger side as well.

I suspect I may have a slow leak though and will keep an eye on it.

:thumbup:Thanks Alex. You were right on....Boy am I relieved... I love this forum

jenshields · Sep 8, 2010

I did it! Have never done a single car repair in my life, but my husband is in Afghanistan and I'm stuck at home with two little kids and the BMW dealer and repair shop are both 30 minutes away. Followed the instructions and now the AC is blowing cold again. Hallelujah!

One small issue, though...as I was wrestling everything back in place to reassemble it, I managed to pop the metal rod off the control motor. When I finally got the control motor back in place, the rod was back in the top (resting in the round yellow disc) but I don't think it was snapped in or attached. How important is that piece? Any idea what will happen? Hope I haven't made things worse...

Starless · Sep 9, 2010

Jen, welcome to the forum and congratulations on the first repair!

My understanding (although I'm not 100% sure) is that the function of that motor with the rod is to switch between the outside airflow and recirculation of air withing the cabin. If my understanding is correct than this system will not work properly with the rod disconnected. I use this function occasionally and could definitely live without it. But I also like everything to work 100% in my car, so it's up to you how important this is

DIY: FSU (aka Blower Motor Resistor) replacement pictorial guide

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