Replacing Final Stage Blower Resistor pack

[jakeg]

ok, sweet, thanks!! i'll tackle the capicator issue this weekend. BTW, where are you finding the Final stage for $80? Bimmerparts has it for $102+shipping, anywhere else i can check to get a better price?
thanks!
Jake

[huckleberry]

Thanks for the writeup DeeM3. I have been looking for someone else with this problem for months. I think what I have is the same thing, can you tell me if this is what your car was doing?

First of all, it was erratic, sometimes fine, sometimes not working. My AC compressor was working fine, cold air was produced, but it felt like a door in the dash vent wasn't opening or something. The fan speed will increase, and I can feel the cold air trickling out, but it is like there is a door closed or something (yes I checked that I had the vent open).

If I have the AC on and the temperature at 60 (digital climate control), this happens. If I turn the AC off, it will open up. If I turn the temperature all the way up (with the AC still on) it will open up.

Is this what was happening to you?

Thanks

[jakeg]

Mine is different. the vents are opening and staying open, just my fan speed gets that gets erratic. Every other function with the a/c works fine. A/c blows cold, vents will stay open, in fact i can control which vent it needs to blow out of with the controls. yours sounds a bit different.

[DeeM3]

I think that's what I paid when I went to the dealer. I'm sure the difference is because the dealer around my way does have good prices plus I get a shop discount.

[DeeM3]

Thanks for the writeup DeeM3. I have been looking for someone else with this problem for months. I think what I have is the same thing, can you tell me if this is what your car was doing?

First of all, it was erratic, sometimes fine, sometimes not working. My AC compressor was working fine, cold air was produced, but it felt like a door in the dash vent wasn't opening or something. The fan speed will increase, and I can feel the cold air trickling out, but it is like there is a door closed or something (yes I checked that I had the vent open).

If I have the AC on and the temperature at 60 (digital climate control), this happens. If I turn the AC off, it will open up. If I turn the temperature all the way up (with the AC still on) it will open up.

Is this what was happening to you?
Thanks

Man 2005 is the year of the AC. Anyway I start replacing the capacitor on your digital climate control. There's a couple of ways that at first they start acting but then they all eventually have the same fate they kinda die.

[DeeM3]

Also do a search and you'll see how other people's AC units act when they're getting the problems.

[jakeg]

DeeM3, thank you for your help! i'll keep you posted on how it comes.
thanks!
Jake

[huckleberry]

Man 2005 is the year of the AC. Anyway I start replacing the capacitor on your digital climate control. There's a couple of ways that at first they start acting but then they all eventually have the same fate they kinda die.

So this isn't what yours was doing?

I dont' have any problems with my screen, and your post was the first I have seen that resembled the same problems I have been having.

But if I understand, you are saying that my problems are not the same as yours, right?

[jakeg]

correct. the only issue i'm having is with the fan speed getting wacky. the vents work fine, so does the display. no other symptoms/issues other than the fan speed going crazy.

[devilbones]

I have the same problem as you jakeg. My AC works but no matter what speed it is set to, it will blow whatever speed it wants. I would like to get this taken care of soon.

[bitchincamaro]

If it was your capacitor in your CC unit, your whole unit would go on and off, sounds like you should go for the other thing first

[jakeg]

i'm thinking the same. i still think its the fan resistor pack. anyone experienced this exact same problem and found the fix? i'd hate to do this via trail and error.
thanks!!
Jakeg

[Ronald]

I have the 96 M3 and have experienced a similar problem with the airconditioner. One minute the unit lights up and the cold air starts blowing and then it all shuts down. When the climate control is working normally do the lights on the unit stay on permanently?

[jakeg]

The display works fine, it will never shut down or turn off. All that the system does is the fan speed goes crazy.

[Griz]

Hmm, I'm having a similar problem with my a/c (99 M3). Some times it will start up fine, but then in the middle of a drive (more often on 90+ days) it will just kick back to the lowest fan speed, but the air that comes through the vents is still cold.

Thanks for the write-up, looks like I'll have one more thing to do this weekend.

[G. P. Burdell]

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.

[VitSports6]

Many thanks on the write up, I was having intemitent problems, I figured it was the FSU, So with a little searching, I found a replacement on ebay.....$58.00 with shipping! Also go figure I replaced a faulty French part with a Good new German replacement?!? The job only took about 20 min, I didnt want to break the dash goodies.
Thanks again!

[mfranz8]

Thanks a lot for the write-up. That gremlin was driving me nuts! I was dreading another trip to the mechanic since I just had the UUC short-shift kit installed and had the water pump and guibo replaced.

[DeeM3]

Glad you benefit from it.

[Rob2nd2no1]

98 318i
my blower quit working along with a burning smell.

I replced the Final Stage Unit and the blower worked very well for five min. then quit again. I now want to replace the blower motor resistor but have no idea where it is or how to remove it. THANKS!!!!

-Rob

[G. P. Burdell]

I replced the Final Stage Unit and the blower worked very well for five min. then quit again. I now want to replace the blower motor resistor but have no idea where it is or how to remove it. THANKS!!!!

Your car uses the final stage unit; it does not use a separate blower motor resistor pack. Pre-1996 models with the rotary knob climate control use the blower motor resistor pack to regulate the fan speed, and 1996-up cars use the final stage unit for the same purpose.

[mitch48]

I've read all the posts on this issue and none are quite like mine, as I can determine. My blower will quit for just a couple of seconds, then pick back up with what seems like even more power than before. I ordered the resister pack, got the old style final stage unit and returned it, found a "porcupine" unit(FSU) that I knew was good and installed it, and the blower still quits sometimes. It will take it in spells, and sometimes never quit on a trip, other times quit every few minutes for a while. I suspect some soldered joint or capacitor is going bad, but cannot confirm this.

[neck]

is there a way to jus take out the FSU and wire in new resistors of my own instead of paying 100 for a whole new unit?

i've yet to take it apart and look.. but has anyone done this?

can't i just use my DMM and check the resistances, apply ohms law and replace the broken resistors?

btw. to save me time, does anyone know the specs for the FSU?


nk

[G. P. Burdell]

is there a way to jus take out the FSU and wire in new resistors of my own instead of paying 100 for a whole new unit?

i've yet to take it apart and look.. but has anyone done this?

I just had a look at the failed final stage unit that I pulled out of my car a couple of weeks ago. There's no obvious way to disassemble it. The end with the plug is permanently sealed with some sort of plastic or epoxy.

[hellrotvic]

is there a way to jus take out the FSU and wire in new resistors of my own instead of paying 100 for a whole new unit?

i've yet to take it apart and look.. but has anyone done this?

can't i just use my DMM and check the resistances, apply ohms law and replace the broken resistors?

btw. to save me time, does anyone know the specs for the FSU?


nk

I don't think it is an actual resistor pack like the older ones. The new ones probably consist of a FET because the blower motor is PWM controlled. But then again, I didn't disassemble mine to confirm, I replaced it, looked at the old part and chucked it in the trash.