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

Thanks for this post. Fixed my 530I good as new!!

thanks for the help. this worked for my 00 bmw. Takes about 11/2 hrs if your 6 ft tall or above. probably quicker if your shorter since, you need to take off the glove compartment, lower air duct and have to maneuver quite delicately to access it and redo it again once complete. the diagram posted is quite similar to what you see, but you need to remove the air duct for access. Have fun

Originally Posted by moorbygp

Put unit in today. everything works fine. Unit was £20 from eBay. So lots of money saved here!.

And, here is what I measured between each pin and ground (the FSU body):
#1: Old FSU = 6.6 ohms, new FSU = 10 ohms
#2: Old FSU = 0 ohms, new FSU = 1000 Kohms
#3: Old FSU = 0 ohms, new FSU = 900 Kohms
#4: Old FSU = 0 ohms, new FSU = 600 Kohms
#5: Old FSU = 0 ohms, new FSU = 1674 Kohms

For comparison, I have my new unit measured today. Counting from the bottom 3 pins to the upper 2 pins. Pin #1 is the bottom left one. Measurements are to the unit's "fingers".

#1. 0 Kohms
#2. 1205 Kohms
#3. 600 Kohms
#4. 595 Kohms
#5. 1205 Kohms

It seem like pin #1 is the unit's "fingers". I therefore continued to measure the values between each on of the pins: ("2-3" means the measurement between pin #2 and #3.)

2-3: 635 Kohms
2-4: 611 Kohms
2-5: 0 Kohms

3-4: 23 Kohms
3-5: 630 Kohms

4-5: 608 Kohms

No measurement for the old unit. It's still in the car...

mw

Fantastic clear instructions. Saved me a fortune. But you guys must have tiny hands to push down that tab and pull out the FSU at the same time. Took me 1-1/2 hour.

Taking off the cover under the glove box was a challenge. Have to pull down the back, then slide it toward the seat

Thanks

Originally Posted by MatWiz

For comparison, I have my new unit measured today. Counting from the bottom 3 pins to the upper 2 pins. Pin #1 is the bottom left one. Measurements are to the unit's "fingers".

#1. 0 Kohms
#2. 1205 Kohms
#3. 600 Kohms
#4. 595 Kohms
#5. 1205 Kohms

It seem like pin #1 is the unit's "fingers". I therefore continued to measure the values between each on of the pins: ("2-3" means the measurement between pin #2 and #3.)

2-3: 635 Kohms
2-4: 611 Kohms
2-5: 0 Kohms

3-4: 23 Kohms
3-5: 630 Kohms

4-5: 608 Kohms

No measurement for the old unit. It's still in the car...

mw

I measured my old FSU and got the following readings:

#1 to all the 4 other pins reads around 8M-9M ohms

2-3: 0.8Mohm

2-4: 0.7Mohm

2-5: 0 ohm

3-4: 1.2Mohm

3-5: 8.6Mohm

4-5: 7.4Mohm

I want to thank the guy who posted the step by step instructions on this. He did an awesome job with the pictures and simple instructions. I am a girl who loves her BMW and did this by myself. I had a mechanic tell me that it was my blower and it would be $1000. After researching this site, I knew this was the problem. It works like a charm.

$90 from the german auto parts store instead of $140 from the dealer. it's too hot in FL today to wait on mail order. It took 20-30 min, perfect instructions. saved me $$$, the hardest part is always the diagnosis

Thanks for this post. My wife's X5 started having the same problem, and I was able to make the switch with your instructions. Took a little longer because removing the panel is a little different (plugs instead of clips) and I don't have small hands. But I was done in 30 minutes with a fully functioning a/c and no more battery drain.

THANK YOU ELVIS530i!!!

I drive a 2000 528i with 62K miles.
Drove home the other night in bumper to bumper traffic, 90 degree heat, and AC was on low. Suddenly the blower went crazy -- like you said, seemed possessed -- I couldn't get it off "high" and when I turned the car off, it just kept blowing - with no key in ignition. Worried about running down the battery, I found directions on finding the right fuse (up behind the panel under the glove compartment) and was able to disconnect that. Then I found this post, ordered the part ($70), drove without AC for a few days and fixed it myself tonight, following your step-by-step directions. Please note I have never so much as changed the oil in a car myself, but just couldn't stand the idea of bringing it to BMW repair, which is never less than a thousand bucks, in my experience, no matter what the problem is . . . Took me 30 minutes, and much of that was trying to find the right plug and then unhook the FSU (agree with the poster who said you need small hands!) Car running perfectly now. THANK YOU!!!

Thanks for the instructions for this procedure. I have been able to remove the resistor and should have the replacement today form UPS. I have a question that I need assistance. The reason I did this was yesterday when I tried to override the Auto AC function all of a sudden what smelled like electrical smoke coming from the front dash. When I pulled the resistor it was obvious that was the cause of the smell and smoke. Is this an indication of something else or was the resistor just bad?

If anybody needs to refer to ANY picture, or need to see ANYTHING with regards to the FSU DIY or any of the parts on its way...

This thing is so hidden, and it is so difficult to explain in words to the new FSU victim how and what... So my hope is that anybody can use these pictures either to help to explain to somebody, or to study before you tackle this very easy job (when you know), or very frustrating when you don't know.

I have posted some 55 pictures at the link below! ( I know... crazy... LOL)....

Nobody should take more then 30 minutes top to finish this job after studying these pictures.

Click here: Reference - Final Stage Unit - The Photo Library - All Useful & Useless Photos.



mw

Thanks for the detailed post. I would like to add that the removal of the cover under the glove box is just as described. However, as I was leary about breaking something, I didn't pull (out - toward the rear of the car) hard enough initially, and was thus delayed by ~20 minutes while I tried to work around this cover. It still only took me ~35 minutes.

Thanks. It took me 20 minutes (included a 10 minute break to look at the pics a couple more times).

Thanks for the pics. made the job super fast. 20 minutes out, 15 minutes back in. Great post. Thanks

Had the symptoms described and replaced the FSU yesterday. Everything seemed to work fine again, but this afternoon the blower motor stopped running again at any speed. All the Climate control functions light up & work, but NO blower motor. After pulling the FSU out again, I could turn the blower motor with my finger. Any ideas???? I've got a 90 degree week coming up & I do not want to try another FSU, any suggestions would be helpful. Thanks

Originally Posted by moosh_cufc

Thankyou so much for this post!
After 4 occasions this weekend where my battery had insufficient charge to start my e39, a quick search on bimmerfest gave me the solution.
£59.00 incl vat for the fsr, or hedgehog as my stealership referred to it as, and then reading ALL of the replies to your post, after I couldn't find the thing in the car (I'm a right hand drive and it's on the drivers side!!!) I'm all fixed

Many thanks

Ian
'02 520i

Hi Ian

I was having the same problem with my 2002 E39. After cheching the forums i found out about the FSR and replaced it , and everything is working perfect. However i did have some concerns about how hot the resistor becomes when the heating is turned on which did alarm me, i mean it gets so hot it would burn your hand, did you notice this with yours ? can anybody tell me if this is normal.

Homer J

Originally Posted by holmesg

it gets so hot it would burn your hand ... can anybody tell me if this is normal.

Does anyone actually know how this FSU/FSR basically works?
And how to test if it's bad? (other than just replacing it w/o thinking ... which is what most of us did)

The best I can glean from the wiring diagrams and threads where people took it apart and actually fixed the bad solder connections is the following (perhaps incorrect) summary.

Can someone take this FSU-test-procedure from here and explain how this FSR actually works & how to test it?

How the fsu is wired:
Pin 1 = (bottom left) to wiring diagram #31; then to battery negative/ground (-)
Pin 2 = (bottom middle) to fuse F76 (40 amp); then to #30, then to battery positive (+)
Pin 3 = (bottom right) input to fsu from heat/ac module, #15
Pin 4 = (top left) output power to the blower motor? (speed 1?)
Pin 5 = (top right) output power to the blower motor (speed 2?), #I5, Ignition power (RUN & START)

Test procedure, from this thread ...
Pins 1 (SW/GN wire) and (5 RT/GN wire) are the negative and positive to the blower motor (right???)
- If you ground pin 1 and apply 12 volts to pin 5, the blower motor should operate; otherwise the blower motor is bad.

- If you test resistance between pin 1 and the metal chassis fins, you should get zero ohms (right???)

- Test if pin 2 (the fuse 76 circuit) has 12 V when the HVAC button is switched on.

Thank you, Thank you, Thank you.

I'm new to the site, and a new owner (April) of a 2003 540i6 black on black, 48k miles, I've put 4k since purchase. I think the first owner washed/waxed the car weekly and I'm trying to continue the trend. I think I'm supposed to say "hello" somewhere else.

Nervously, I paid $115 plus tax for the part at the dealership this afternoon. They quoted $287 to make the repair, stated it would take 1.5h of labor. I finished in under 30min and that included periodically checking on my child playing inside. My only real issue was getting the screw back in through the carpet. BTW, I also replaced the cabin filters last month, dealership wanted $165 for both, bought the pair online for $54 total.

Hi

This is a great DIY post!

I got a 530i -2005 (E60) and i can't find the FSU.
Is it hidden behind something else? Because it doesn't look the same as in a E39.

I did this last night. Putting the passenger seat all the way back and fully reclined lets you slide head first under the dash and get at the part. My 14 yr old son had a brilliant idea. He has an LED camping headlamp and I used that so I could have two hand free. Be patient and its easier. I'm 6'1" and 230lbs and don't fit well in tight spaces.

Oh well, the write up was great but unfortunately i'm going to have to get the control unit (i think). Replaced the FSU this morning but nothing changed. Messed up part is the control unit on the site that i got the FSU for 60 bucks wants 600 bucks for the CU.

Another satisfied customer over here... did this lastnight and hardwired my Valentine while I was in there, pretty easy as repairs go, just some sore fingers from all the pinching, pushing, pulling, etc in there.

Elvis, Fabulous post with solid pictures and instructions. As with many others, I just wanted to personally thank you. rlarge1949

I used my right hand only. took less than 5 mintues to unlip the harness then pull the old one out. all went back in no problem. take off the side carpet panel and under glove box cover. heres where i ordered it from. they wer echeapest, free shipping and part came in 6 days. this wa sfor 2002 525i


Part #: 64116923204-58
KO Price: $54.04
Shipping: $0.00 - FREE Shipping! - & *Ship Group

http://www.koperformance.com/online_...D%3A1%3B&hl=en

Just a thanks to the original poster of this. With the DIY pictures and directions this was an easy fix to my E39. Part was 80.00 from Bavarian and about 20 minutes max. Beats the hell out of what the dealer quoted at $300.00.

Thanks for sharing and taking the time to put pics, made it really easy.