Replacing Final Stage Blower Resistor pack

[djpfine]

I had the same symptoms a while back.
I bought the FSU and installed it into the car. My blower did not start working again. I put the old FSU back in (blower still not working).

Then I tore down to the actual blower which is accessed at the back of the engine compartment (or just rear of it). The blower motor was properly connected electrically. Yet apparently the connectivity had degraded over time to the point that current did not pass to the motor. Depending on which way I wiggled the wire, the motor would work or stop.

The fix: loosen the screw that secures the wire to the motor. Wiggle it around a bit and then tighten the screw. The motor worked immediately and has ever since!

Lesson learned: given the symptoms at the beginning of this thread, don't automatically assume that you have a bad FSU or blower motor.

To fix my blower issue, it cost $0.00 and 1/2 hour of my time.

Is the blower easy to access? I'm not a big DIY guy.

[G. P. Burdell]

Is the blower easy to access? I'm not a big DIY guy.

The blower is accessible from the engine bay. It is located below the air intake plenum at the firewall. You have to remove the plenum and move the big wiring chase above the engine out of the way to get to the blower housing. After getting the cover off of the blower housing, you have to destroy the old blower wheels to get them and the old motor out of there. A new blower motor will come with detachable fan wheels that you attach to the motor shafts inside the blower housing.

The steps are not especially difficult, but the blower housing is a cramped space.

[Miggl]

My HVAC had the following symptoms:
- During colder weather I would hear 'chirping' from the blower, as if the bearings were going bad. This stopped as winter turned to summer (I'm in LA, so it doesn't get very cold even in the middle of winter).
- I left my car sitting for a month while I was traveling outside of the country.
- Came back (after said month) and started my car. Now the blower made sounds as if it was hitting something in the blower case (like the card-in-the-spokes on kids bikes).
- The blower just stopped one day (wouldn't come back on when I started the car).

Now, since the blower is not working, the climate control unit is fully lit and functional (I did the capacitor replacement last year), how do I determine if its the Final Stage Resistor or the Blower motor gone bad?

Thanks for a great write-up!

Mike

[Miggl]

You can do a little diagnostic work if you have a multimeter and the Bentley manual wiring diagrams.

When the key is in the ignition and turned to the "run" position, one pin on the plug that connects to the final stage unit should receive 12V power from the blower relay. When the climate control unit is on and functioning properly, another pin on the plug should receive a variable "control voltage" ranging from 2 to 7 volts, depending on the fan speed shown in the display. Adjust the fan speed up and down and watch the voltage change. Supposedly you can also insert a jumper wire between two of the pins and make the fan run at full speed, although I haven't tried this.

Last week, I did what I outlined above (except the jumper wire bit) and determined that the final stage unit was most likely at fault. I replaced it with a new one this past weekend.

I tried this, however, this will only measure if the resistor pack is receiving the correct voltages. You still don't know if the resistor pack is bad, or if you need a new blower, without using the wire-jump-method. Does anyone have a wiring layout for the plug that goes into the resistor pack? I'd like to try jumping the contacts to see if the blower still runs.

Thanks!

[fuzzylee]

Can some one tell me if i change the final stage resistor will be able to solved my problem....
I have a 96 328i, and some time my AC is not working, some time its working.
when its not working, in the front with footwell air duct it blow Hot air into the car.
Question, Why is my AC acting up weird? And why did the Hot air blow in when AC is not working. When i go faster it blow hotter air then when i go slow.
thanks for helping!

[737ng]

First time poster.
I've got a 94 325i. The blower only worked on high so a mechanic replaced the resistor and every thing worked well for about 2 days. Now the fan only works on high again. Anyone have any idea's on this. I was wondering if the blower itself is drawing too much resistance and causing the resistor to go.

Thanks 737ng

[boeing328i]

My symptoms are Display all working but no air blowing out, and the the CAP. was replaced already, It blows cold in the morning for about 1 minute only to shut off again for the rest of the day. How different is this DIY, from an M3 (on the pictures, I think) as to a '97 328i?, I need to do this like "yesterday" but I'll like to do it right the first time, and how difficult is this job? Thank you. William

[EricP]

My symptoms are Display all working but no air blowing out, and the the CAP. was replaced already, It blows cold in the morning for about 1 minute only to shut off again for the rest of the day. How different is this DIY, from an M3 (on the pictures, I think) as to a '97 328i?, I need to do this like "yesterday" but I'll like to do it right the first time, and how difficult is this job? Thank you. William

Not too bad at all.. most of the work is getting the kneeboard thingie (technical term) and a vent duct out of your way so you can get to the final stage unit itself. As long as you can contort yourself under the dash for a little bit without going into spasms, you'll be fine. I had my final stage unit AND CCU capacitor die on me last summer when it was 105 out. I won't take my cold air for granted this summer!

[Thrizzle]

good Diy page, thanks for your work!

[BEAMERGUY4EVER]

Can some one tell me if i change the final stage resistor will be able to solved my problem....
I have a 96 328i, and some time my AC is not working, some time its working.
when its not working, in the front with footwell air duct it blow Hot air into the car.
Question, Why is my AC acting up weird? And why did the Hot air blow in when AC is not working. When i go faster it blow hotter air then when i go slow.
thanks for helping!

If you are getting hot air out of your AC this is not related to your FSU I dont think. The failing FSU should only be having an affect on your fan's speed. Anyone else have input here?

[boeing328i]

I would like to say that I did change the FSU on my car and that fixed the problem finally, no longer is the A/C acting up, it took all of 20 minutes at a slow pace, very easy DIY, I must add that I got the part at the stealership just to make sure that I bought the right part for my model year, since there is some confusion on several part numbers, for about $127 plus taxes, my problem is been gone now for several days, I will keep an update if something comes up though, but I must thank all the guys that did reply to all of my whining and frustration .

[djpfine]

Does a faulty FSU also contribute to a lack of coldness from the A/C unit? I notice that sometimes my A/C is cold, but sometimes it's barely colder than just the fan blowing.

[boeing328i]

Does a faulty FSU also contribute to a lack of coldness from the A/C unit? I notice that sometimes my A/C is cold, but sometimes it's barely colder than just the fan blowing.

Not in my case.

[dsp420]

Amazing write up!

+ 3

I hope that this is my issue as well. Here is my story.....

Example:

I took my son to school yesterday morning and all was well. 110 outside and the ac was great. I got back home, ran some errands, took a drive on the 101 and all is still good. I go to pick him up later to catch Trasformers (badass!) and EVERYTHING was normal with the CCU, etc... but no blow. I sucked it up and drove to the theatre with 110 air blowing on our faces.

After the show we got back in and what?!?!?!? it works fine, and ran fine the rest of the night.

This morning I take him to school and all is well. I park, drop him in class, go back to the car, and.......

no air! WTF!

It sounds like it has to be this issue that the writeup is on, and if it is that would be great, cause it looks like an easy fix and cheap. Cheap I mean only because I'm not taking it to the shop. F that.

Does this sound like it cold be the resistor? Sounds like the same issue?

Thanks for all the help, and great write-up again.

[boeing328i]

Amazing write up!

+ 3

I hope that this is my issue as well. Here is my story.....

Example:

I took my son to school yesterday morning and all was well. 110 outside and the ac was great. I got back home, ran some errands, took a drive on the 101 and all is still good. I go to pick him up later to catch Trasformers (badass!) and EVERYTHING was normal with the CCU, etc... but no blow. I sucked it up and drove to the theatre with 110 air blowing on our faces.

After the show we got back in and what?!?!?!? it works fine, and ran fine the rest of the night.

This morning I take him to school and all is well. I park, drop him in class, go back to the car, and.......

no air! WTF!

It sounds like it has to be this issue that the writeup is on, and if it is that would be great, cause it looks like an easy fix and cheap. Cheap I mean only because I'm not taking it to the shop. F that.

Does this sound like it cold be the resistor? Sounds like the same issue?

Thanks for all the help, and great write-up again.

F.S.U

[dsp420]

F.s.u. ??

[boeing328i]

F.s.u. ??

Yeah! your year model has a Final Stage Unit and not a resistor,.. if we are talking about the same problem of the a/c acting up... in any case that was my problem.

[dsp420]

ahhh. thanks man. Still learning ya know!?

a

[coop12]

Thanks these we good instructions

[SD96bmw328i]

The front intake fan keeps running when the car is not on, which drains the battery empty. All other controls (AC, etc) work just fine. After reading some postings, everybody refers to the Blower Resistor. After researching , there are two Blower Resistor - Blower Motor Resistor (Part # #R2032-61965) and Blower Motor Resistor Final Stage (Part #R2032-125167 ). Which one should be replaced and where it's located withing a car (96 328i)? Thanks

[vetterx]

Can someone post a pic or let me know what wires go where? The previous owner apparently thought that cutting the wires and soldering them to the pins was a good idea. i Bought a new FSU and just want to make sure i put the correct wires to the correct pins.

[vetterx]

[M threezy]

thanks for the write up! replacing the part worked wonders!

[Sammy Sileage]

Just wanted to add, if you are from the UK like me, to save you time, the Final Stage Unit is on the passenger side of the car. My problem was no blowing at all but the display still all working, changing the unit fixed this. Helped me alot. Cheers.

[mr rolleyes]

ok diagnose me...

i have no air or heat pushing from the vent at ANY speed. when i turn the ac on i can hear the compressor kick on.

i bought a fsu and that did not do the trick...

so im down to:
1.blower motor
2. cc resistor
3. resistor relay

what is most likely my issue?

thanks