Most of the time in fan circuits over heated connectors are visible, sometimes discolored or actually burned, same with the ground connnection. It may feel tight byt not be making good contact. Wiggle tests can also be useful here, just wiggling wires checking for a response.
Almost definitely the final stage resistor. It is located behind the glove box, to the left.
There’s a slight chance that it is the IHKA (climate control unit, includes the buttons and display) but that should only be changed as a last resort after investigating the FSR.
The third component in the E46 unholy trinity of climate control problems is the exterior temperature sensor, located in the front left wheel well. That will cause the exterior temperature display to be wildly incorrect.
Yes. I found this yesterday also, and I wrote a reply to this thread asking a few questions. I guess i hit the “preview” button instead of submit, but that’s where I learned about the Final Stage Resistor (or FSR)
Terry,
After some googling and reading on the bmw forums, like bimmerfest.com, two things jumped out.
The first was the FSR. However, the second thing was a fuse. Interestingly, someone said that they read that BMW suggested to pull out and reinsert a fuse that controls the FSR. According to the post, the FSR will be reset with this, and everything will run again normally.
A few folks posted that they had success with this, so I am going to try it first, if it doesn’t work, the FSR seems to be the problem according to my symptoms and what everyone else on the BMW forums suggested.
I do have a couple of questions regarding the fuse issue:
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should the car be on (engine running) when I remove the fuse and put it back?
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if the engine should be off, should the battery be turned on with the key being set to the Alt. Curr. Setting? (This is the setting that permits you to listen to the radio while the car isn’t running… It draws power directly from the battery without recharging the battery).
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should i just remove and reinsert the fuse without putting the key on alt current or starting the car, which would minimize battery power draw to the minimum without disconnecting the battery?
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should I disconnect the battery first?
My plan is to do number 3 first. Remove the fuse while the keys are not in the ignition. I am not exactly sure how pulling and replacing the fuse will reset the FSR, but perhaps the FSR is one of the systems receiving some power from the battery without the car running (like the auto door locks, which receive battery power so they can be opened without the engine running or the battery being used directly with the Key turned to the A/curr mode.
Any thoughts? I don’t think there should be any issue with removing and replacing a breaker no matter how I do it (as long as I do it correctly). I just want to make sure I don’t overlook something that could cause me heartburn later on.
I am going to do this later today, so I will report back with my findings. It will be sweet if the resetting of the fuse is all that needs to be done here, but replacing the FSR IS something i can do myself. It is apparently a tight job, considering where it is located, but it is very doable.
It is unlikely, but it is an easy thing to try.
You can pull the fuse with the key out of the ignition. I don’t think it is a circuit that is always live, though. If you don’t care about things like accumulated fuel economy readings, etc. you could just disconnect the battery, which is guaranteed to reset everything that can be reset.
The annoying thing with the FSR is getting the glove box out. Empty it out first. When you put it back in, there are large plastic pins in the back that need to go into the matching metal tab holes on the frame. If you don’t get them in properly, the glove box will wobble and rattle.
If you need the detailed instructions, let me know and I’ll pull them off the disc and post links for you.
I highly recommend having the ignition key in your pocket when you’re changing automotive fuses.
It’s sort of a toss of the coin: There’s a lot to be said for checking the most likely failed component first. On the other hand, there’s something to be said for checking the not most likely to fail but easiest to access component first also. If you know how to interpret what the DVM is telling you when you check the easiest to access component, it might help you diagnose the failure.
After reading up the fsr does sound like the candidate.
The fuse was the culprit.
All I did was pull it out, examine it (it was not blown) and reinserted it.
Then, I put the key into the ignition and started the car. The fan blows perfect again, including going all speeds (i checked to make sure the fan just wasn’t blowing at one speed. I then put the A/C on, and no change. The cold air came out as always.
Very happy with this fix, and i am so glad I read the entire thread I found on (I think it was) bimmerfest.com.
The first half of the thread discussed changing the FSR, which did not scare me, since there are a few DIY videos on youtube. However, I figured the Fuse was an easy check, and sure enough, that was the ticket.
Which begs the question… What happened? What is it that was somehow knocked out of sync, and when removing and replacing the fuse, what was reset?
Very strange one. But for once, it worked out the easy way.
Thanks all for your help!
It wasn’t the fuse. Fuses are either good or bad there is no sorta good, or sometimes good with a fuse Just like you didn’t get your girlfriend sorta pregnant, your fuse isn’t sorta bad.
Despite it’s name the FSR isn’t a conventional resistor pack. it is a mini electronic control unit that uses a rather large power transistor to vary the fan speed in response to signals from the control head. did you see those long aluminum fingers in the video? that’s the heat sink for the power transistor.
by pulling the fuse you removed power from the FSR and allowed it to “reboot” to a normal condition
Thats a good example of how often parts are changed that don’t need changing. Changing the FSR would have fixed the problem even though it wasn’t the problem. Toward the end of my mechanic career smart switches and controls that worked off of mega hertz were being used, few of us myself included took the time to really learn them and would often change parts we didn’t need to change, always felt bad about that when I had to deal with it.
Rick,
Thanks for posting. Obviously, it wasn’t the fuse. As you said, it is either good or bad. But pulling it out and putting it back in reset something within the FSR itself.
I did see those long aluminum fingers in the video, and I wondered hoW the thing worked. I had never seen an FSR before, so this whole thing was new to me. I learned a lot about my car that. I didn’t know before.
I also found a video showing how the fan motor itself is replaced, which is something I hope I never have to do, but I am pretty sure I would be able to if I needed to do it.
I was thinking how often this part has probably needlessly been replaced, and how much money has been spent needlessly on the repair. The new unit is a lot different than the old one, but most people would never even see that (unless they are like me and request the old part that was replaced to be returned to me.). I would imagine the unscrupulous mechanic who knows about the fuse solution could make a nice chunk of change by spending a few minutes doing what I did.
The customer would take the car in, have it diagnosed as a bad FSR, and that would be that. When the customer would come by and pick up the car, the fan would be working properly, and they would have probably spent around $200 for the repair. That would suck if the only thing needed to happen was to reset the DSR by pulling and replacing the fuse.
I wonder how many BMW mechanics know that this is one possible fix? I imagine some sort of service bulletin was sent out, as that seemed to be what happened to the person who posted this potential solution on the BMW website. But I imagine there are a number of mechanics that would have forgotten about the fuse or never knew about it in the first place. Changing the DSR isn’t that hard, and it would take an experienced mechanic less than an hour.
One final note: BMW enthusiasts are really into fixing their own cars and modifying them if they can and there is a ton of info out there on the web. I don’t know if other cars have that kind of following, but there are a few BMW repair forums out there that you can get great info from.
The official service instructions state something like “You may find removing part of the engine block helpful” :eek:
One trick is to use the blower from an X3 (you’ll probably need to re-use the wires from the old blower as the X3 ones are shorter). The main PITA is that the screws fall down into the air conditioner coils and become nearly impossible to remove.
The upside is that it makes it very easy to “de-skunk” the climate control system (comes from mold growing on the coils). BTW, the official BMW tool for this is a sprayer that goes in… wait for it… the opening for the FSR.
I found a DIY video on youTube that showed the mechanic removing the top pieces of the engine block. There are two sections, one overlapping the other. Once these are off, it permits you to get to a few things more easily, as the blower is underneath the cowl, right against the firewall.
There are definitely a number of things that have to be moved out of the way, which could be a pain in the ass (or as you point out, dangerous, as dropping screws can be a real problem.). The DIY video talked about the screws and how dropping them by mistake would be a bad thing, so he showed how to remove them by holding a magnetic wand next to the screw driver, something I own but would have never thought of using until seeing the video.
I think the hardest part of the job would be the removal and replacement of the screws… Nothing to sneeze at for sure. And if you have shaky hands or don’t want to risk losing a screw, i don’t think having a trained mechanic do this one would be a bad idea.
Keep in mind that the fan could be fine, but the themo sensor (helping the controls decide when it should be on and how fast it should go) or the controls could be failing. To check this, see how well it works in manual mode. If it works in manual mode, then don’t bother trying to fix the fan!
Unless you’re in the habit of auto maintenance (or plan to get into it), I’d refer this to a mechanic. Fixing what you bungle could cost more than you might save by fixing it yourself.
Note, I’m a big DIY fan, but a while back, when I realized I couldn’t change a spark plug on my minivan without the equivalent of a dental mirror and double-jointed wrench, I decided it was time to let the pros fix my car. I even resorted to having my mechanic replace a headlight recently; I just couldn’t get my damn fingers (or any tools) into where they needed to be to secure it, and when I looked at how many parts I’d have to remove, the answer was clear.
But do get a multimeter or volt-ohm meter (aka VOM)! You can get one for $15 or less at Radio Shack or any hardware store and it will help you sort all sorts of problems. I use mine regularly, most commonly just to check for connection vs no connection (ohm-meter mode with beep for connectivity).
A multimeter may add ammeter capability to a VOM (and maybe other stuff). Ammeters are trickier to use. If you don’t know what you’d use one for, it probably wouldn’t be very helpful. But heck, it can’t do any harm … unless you use it wrong. 
Think about this.
You car is 11 years old. It never had an FSR failure until now. What changed to cause the failure? The answer is something in the FSR. By pulling the fuse you cured the symptom, but not necessarily the cause.
Now one of two things will happen. Either the problem will reoccur or it won’t.
If it never reoccurs you are golden if it does reoccur you aren’t.
There is at least a good chance that the failure will repeat and with each repetition the time interval between failures becomes less and less.
Now you might be good with pulling the fuse every few days, I can tell you the average customer isn’t.
If the failure reoccurs, with the average customer, it damages the shop’s reputation and jeopardizes future business from that customer.
I have done quick no charge repairs like this for customers and then had complaints when the problem comes back. Nice. No good deed goes unpunished.
I’m not saying I don’t or won’t do quick fixes like this, but I do a careful read on the customer first.
I do hope your problem does not reoccur.
I am not sure what you are trying to say here. Did something I write offend you? Because that wasn’t my intent. I did think that you are a mechanic or know a lot about cars because your name seems to show up in car threads, but if I am wring, my apologies.
If you are giving me fair warning that my car is 11 years old and that resetting the FSR by pulling and replacing a fuse is a band-aid and not a complete fix, I agree with you. I know a bit more about cars than your average guy, but I am far from a certified mechanic. However, I do my own oil changes and brake jobs, (both drum and disc) including rotor replacements, light bulbs, etc. so, I am not afraid to pull a fuse.
Is the average person confident enough to do this? I don’t know. Probably not. But I am not advocating anyone else to do this on their own if they can’t do it. I am also not suggesting that every mechanic should tell each customer that comes into his shop with this problem to just do the fuse trick. Everyone is different. If my wife, for example, had this problem and the mechanic told her that if she pulled the fuse and replaced it, it would fix the problem for an indeterminate time, or if she wanted to have a more permanent solution, she should have the FSR replaced, she would have had the FSR replaced.
For me, this is a good fix. I don’t know when or if this will happen again, but if it does, I will not be afraid to do the fuse trick again. If it happens within a month or so, I will probably just replace the FSR, since replacing it is the only sure way to fix it permanently.
The other thing to keep in mind is that when I read about the fuse solution, the person who wrote it mentioned that the information came from BMW. That was one of the reasons I figured it was worth a try. There were a number of people in that particular thread that had both changed the FSR and pulled and popped the fuse, and no one had come back to share that the problem had reoccurred.
Who knows what caused it to misread? Could it have been caused by a disconnected battery? I don’t know. But my car was in the shop recently and the battery was disconnected for a time. I have yet to find someone who can tell me WHY the FSR started acting strangely and what information gets reset inside when the fuse is pulled, so that would be interesting to find out.
I have looked at the part (as I believe you have). That is a solid state part, correct? No moving pieces? What, in your opinion, could have happened to cause it to glitch? As I mentioned, my radio was reset, the seat no longer had my settings, and this problem with the FSR occurred, i noticed all of these things at the same time, so I am wondering if the power interruption caused the problem.
I don’t know. I’d be interested to find out. But my wife suggested before this spring that I should get a new car, so I may not have it long enough to worry about it again. My fingers, as always, are crossed for luck.
I won’t be trying to fix the fan any time soon, no matter what. A re-viewing of the DIY clip made me realize that losing or dropping a screw is a real possibility here, and i have no desire to cause that problem for myself. If a BMW mechanic does it, I have two things going for me. 1) I don’t have the responsibility of fishing the screw out and fixing the thing properly, and 2) my dealership gives me a free rental car for as long as my car is in their shop, so if they happen to drop a screw or something like that, they can take as much time as they need to take to find the screw and fix everything properly. They give me a brand new BMW as a loaner, so it works out just fine for me.
I have learned this the hard way too. As Clint Eastwood said, “A man has to know his limitations.”
So yeah, i have screwed the pooch a couple of times in my life. A fuse is easy for me, and should be for most people. Most BMW’s actually come with a plastic fuse puller, which can also be used to grip the tip of the fuse while you put it back.
[QUOTE=Rick]
You car is 11 years old. It never had an FSR failure until now. What changed to cause the failure? The answer is something in the FSR. By pulling the fuse you cured the symptom, but not necessarily the cause.
[/QUOTE]
[QUOTE=Stink Fish Pot]
I have looked at the part (as I believe you have). That is a solid state part, correct? No moving pieces? What, in your opinion, could have happened to cause it to glitch? As I mentioned, my radio was reset, the seat no longer had my settings, and this problem with the FSR occurred, i noticed all of these things at the same time, so I am wondering if the power interruption caused the problem.
[/QUOTE]
My WAG is that this car embodies the “What if Microsoft Made Cars?” gag, and the controller just needed a good clean reboot.
FTR I have spent my adult life working on cars, teaching about cars (for a car company) and managing shops. Yes I am a Certified Master Automotive Technician. And yes I found both your comments and those of HoneyBadgerDC to be somewhat insulting. Let’s look at what you said.
Information came from BMW. OK remember that, it will come up later.
Disconnecting the battery will cause the radio to forget stations and memories for seats etc to be forgotten. I doubt it caused the FSR failure, as disconnecting the battery does exactly the same thing as pulling the fuse.
Since you have no clue as to the potential longevity of the pulling the fuse repair, how can you say the part was replaced needlessly? You have no clue.
If it looks different, that means it was redesigned. Car companies don’t redesign for shit and giggles, they do it for a reason. What reason could they have to redesign a FSR? Could it be the prior design was a piece of shit?
Got a broad enough bush there? As I have already told you, you have no clue as to the potential longevity of pulling the fuse repair, so you aren’t qualified to comment. And when the POS FSR fails the next week, he gets to fix it for free. Doesn’t sound like a real good business plan to me. Oh wait, I forgot we are all knuckle dragging thieves.
Home Depot having a sale on broad brushes I see. Remember up a few paragraphs where you said the info came from BMW? A competent quality shop would know this information, and use it. But if you insist to taking your car to someone that does not have the proper diagnostic tools, subscriptions just because they are cheaper, well then part of the blame lands on you.
Stink, please tell me what profession you are in so I can insult them (and you indirectly) in a thread.
Mega hertz?
WTF?
Please name me the year, make, model, and system that has switches that work on mega hertz. That is a radio frequency. So unless you are talking about the RF remote to unlock the doors, I highly doubt you know what you are talking about, which calls into question your comments about changing the FSR.
Rick, these are on trucks maybe starting 8 or so years ago approx. The devices naturally operated on 12 volts but the switching was controlled my megahertz which I admitted right off the bat that I never updated myself on. The instructors in the classes we attended freely admitted that it was often easier to simply keep some spare parts on hand to try out instead of attempting to trouble shoot the systems.
Glitches in a system don't neccessarily mean that a componet that is not operating properly is the cause, I agree it usually is but I would say if it happened twice with no other symptoms I would change that part. He had other systems go out at the same time he said.