Climate Control Issues & Solutions

[racerblade]

If your climate control is out of whack I hope you can learn from my pain, and the write ups from others. All the write ups I've seen on A/C issues focus on either the climate control unit dying, the final stage unit, or in a few cases, on the blower motor itself.

However, I never really saw anything about a blower relay, which is just one of the relays in the fuse box under the hood. This turned out to be the issue in my case (symptoms: digital climate control worked, but the blower would not work at any speed).

In an effort to help folks out, here are the issues that people have listed, symptoms, and reported solutions. It's so nice to have A/C again now that the weather is getting warm :)

Dead Digital Climate Control
Symptom: Digital display is black, no controls respond.
Solution: replace or just resolder a capacitor (link) (http://www.macadamizer.com/bmwfix.html)
FWIW - the 47uF part from Radio Shack works fine - I did this fix >2 years ago, and no issues at all.

Blower Relay
Symptoms: Digital climate control display is on, buttons light up, but no air is moving regardless of the setting.
Solution: it may be the blower relay which is in the fuse box - check Bentley for exact location. The part costs $20 at the $tealer.

Final Stage Unit
Symptoms: Fan only works at highest speed setting
Solution: Replace Final Stage Unit (http://bimmerforums.com/forum/showthread.php?t=292522&highlight=final+stage+unit)
Note: If you have a manual climate control, the part you are replacing is called the "Blower Motor Resistor". Both parts go in the same place, and part pictured in bentley is the resistor.

Blower Motor
If none of these work for you, take your car to a local shop and have them test the blower motor (without removing it). If it's the blower motor, I haven't seen any DIYs on this one, besides Bentley, but apparently its worse than doing a clutch job just b/c it's such a tight area to work in, and you have to go through the firewall. Cost for this one at a local indie in PA with OEM parts is about $680 ($300 parts + labor).

[gbarnes]

Before I tear my dash apart I wanted to ask:

My lights are on, the temperatures are both fixed at 66 degrees, (not where I set them) None of the climate control buttons buttons respond. The "auto " button is illuminated and air is blowing.

Are these symptoms of the capacitor?

[EricP]

Before I tear my dash apart I wanted to ask:

My lights are on, the temperatures are both fixed at 66 degrees, (not where I set them) None of the climate control buttons buttons respond. The "auto " button is illuminated and air is blowing.

Are these symptoms of the capacitor?

Probably, but mine were different. Need someone else to confirm. For what it's worth, however, there isn't any tearing apart of the dash necessary. Just pop out the OBC then the climate control.

[M3BimmerBilly]

Before I tear my dash apart I wanted to ask:

My lights are on, the temperatures are both fixed at 66 degrees, (not where I set them) None of the climate control buttons buttons respond. The "auto " button is illuminated and air is blowing.

Are these symptoms of the capacitor?


Being that the cap costs $1.37 and it only takes 30-45 min start to finish its worth a shot to replace it since its so commonplace.

[al_r]

Replacing the blower motor is not that bad; took me about 1.5 hours the first (and only) time.
If the replacement has new fans (squirrel cages), break the old ones off to remove the old motor. You can get any fan pieces out with a vaccum, down by the the microfilter.

[racerblade]

Well - you won't need to tear anything apart to get to the climate control. But I don't think the control unit is the issue for you. It sounds excactly like what I experienced - look at the first post under Blower Relay.

You need to replace the blower relay - which looks like an oversized cube that sits right in the fuse box. It'll cost you ~$20 and take <2 minutes. Try that first, especially since your control unit appears to be functional right now.




Before I tear my dash apart I wanted to ask:

My lights are on, the temperatures are both fixed at 66 degrees, (not where I set them) None of the climate control buttons buttons respond. The "auto " button is illuminated and air is blowing.

Are these symptoms of the capacitor?

[f4im3]

Great info in this thread.
Got another one for you.
Airspeed out of vents stops momentarily with A/C on and sounds like the mix door opens/closes, then normal operation resumes.
Display is normal and does not change when this happens. Replaced final stage unit and not change.
Any ideas?

[bambam315]

Mine went out on me last week.
The climate control display was working fine but I did not has any air blowing. I can not set to any air level or temperature. It would have a mind of its own, working whenever it wants too. I first change the blower relay that did not help. I then replace the capacitor on the climate control and that has fix the problem. It may be your climate control is slowly giving up on you...

Good Luck

[TB6387]

Well - you won't need to tear anything apart to get to the climate control. But I don't think the control unit is the issue for you. It sounds excactly like what I experienced - look at the first post under Blower Relay.

You need to replace the blower relay - which looks like an oversized cube that sits right in the fuse box. It'll cost you ~$20 and take <2 minutes. Try that first, especially since your control unit appears to be functional right now.

Would anyone happen to have the part number for this relay. I believe mine is in need of replacing and i searched realoem.com but I cannot find this specific relay.

[Eracer1]

I am a novice on this site...having only recently purchased my first Bavarian motor car (98, iS328, 120k). After having sifted and read through the numerous threads on here, I became fully aware of future problems that I may and will eventually incur with the car. This pre-emptive information is very valuable in that it forewarns me to future repairs and expenses, but of course for the ensuing peace of mind as well (my Vanos is acting up, I also am aware from my readings that the blades on my water pump are going to fail etc).

Recently my Climate Control went on the "blink"...and after having searched the countless threads regarding the possible causes and fixes, I started my repair using Richard Swope's article. However, before making any capacitor replacement, I took the disassembled unit, reinstalled it loosely in the car...and tried tapping it lightly...this initiated some of my myriad of symptoms that I was experiencing. Thus, after returning to my work bench, I decided to take the advice of another's members strategy of just resoldering the original connectors. Why invade and alter the circuit board any more than needed if perhaps the fault was a insecure or cold solder joint at the capacitor. I carefully scraped off some of the orange protective coating, heated the joint carefully with a 20 Watt very fine pointed soldering iron, removed a tiny bit of solder using some desoldering braid, and then added a tiny bit of solder to the connectors which I slightly straightened into a vertical orientation, and then enjoyed the shininess of the two newly soldered connections.

At this juncture, still not knowing if this was the correct repair, I went back to the car, reconnected the 2 other harnesses, (the automatic climate control censor fan had already being installed) allowing the unit to sit softy on a pillow. I then started up the car and let it idle. I then proceded to wait...and wait...and wait....trying out all the different functions...with amazingly all systems appearing "go" for another space shuttle Atlantis launch. At this point, with the unit tentatively working perfectly, I then reinstalled the unit into its bracket in the car. I went out and gave it a medium test drive and am ecstatic to report that to date, all CC systems are a perfect "Go!"

(A Few Extra Tips):
1: the black clip that secures the automatic climate control fan bracket must be released from the back of the housing to enable it to slide out with circuit board, squeeze the yellow supporting connector clip on the climate control fan to remove it.
2: The screws 6 of them, 2 on the fan, and 4 on the front cover were mini torx screws that I did not have in my tool chest, but a small flat screw driver will fit across the torx indentations.
3: Pressing the 2 side tabs inward that secure the circuit board in place is tricky if not impossible from the outside of the bracket...for me it seemed better to go in from the front...with a long thin flat screw driver (about 3 to 4 mm wide) ...and insert the blade of the driver between the tab and the bracket housing and basically push/pry out a few mm of the circuit board tab from the housing from the inside. I did this to both sides. It was a bit tedious and trickey...the tab would snap back into its slot after I went to the tab on the other side...but eventually...the tab would stay out enough for me to go to the back of the bracket. At this point, I took 2 thins screw drivers (about the same as the one you used...) and carefully inserted them down at the back of the bracket, but behind the circuit board, this is where is it good to have very good lighting and sharp eyes....because you do not want to puncture the back of the circuit board) and slowly and carefully pried/pushed forward the circuit board about a few mm to break it clear out of the back platic supporting pins that it sits in...the board is held in place in this housing at three points...long grooves on both sides...and about 4 sets of black plastic pins at the back...these are hard to see from the front...When doing this procedure...if a piece of bracket seems to be bending out of the straight plane more than normal...then stop and restart your prying procedure...if something does not seem right...believe me...from experiences...it is not right...I also had a bright fluorescent utility lamp light on the table beside me to give me better lighting to spot the side grooves and back supporting pins that the board rests in...I also am fortunate to own a set of jeweler's head set to magnify things...but you do not need this. Having an extra set of hands would also come in handy...although I did only have one set.
4:there has been some discussion regarding the specs of the said capacitor. Using a magnifying glass, and having the confirmation by a second bystander, the blue capacitor reads: u47M63...where the "u" is the greek letter mu for micro...and I assume the 63 is the voltage. That is what rests currently on my circuit board. There does not appear to be a "decimal point" in front of the 47. ..(by the way...I tried to test the capacitor with a digital meter...as well tried to get readings on my new ones that I purchased...does any out there know how to get readings on a capacitor...just curious...but it would be good to be able to check the capacitor while it is in the circuit board)


I work in the watercraft industry where electrical problems dominate, and if we were to install for instance a new fuel gauge sending unit ( a difficult removal in cramped quarters), before the final installation, it is standard procedure at our shop to pull out as much of the the interior wiring harness outside the watercraft as possible, plug the connectors, and see if the repair is correct at that point. No sense in doing the full install, findout the repair was incorrect, and having to waist all that time and effort to remove the unit again. Thus the suggestions by one of our members (and I apololgize for not knowing his name to credit him at this point) of placing the unit in loosely and tapping it, checking connectors, or just resoldering the joints as opposed to installing a new capacitor when just a partial resoldering will do the trick...are excellent and time saving steps to abide by.

I just want to thank many times over for everyone's contributions on this site, Richard Swope's detailed outline, and especially the unknown member who was able to learn that it was this blue capacitor on the circuit board that was the probable culprit. I would like to extend my final thanks to him as well. The fewer trips I need to make to my BMW dealer, the better for now.

[Soulburn]

Awesome info here, thanks for the post.
I was having problems with my Climate Control unit randomly shutting off and coming back on when it just sort of felt like it. I decided to try replacing the capacitor by following Richard's site information. The entire process went over very well; the hardest thing was simply removing the board from the plastic control housing. But after that i was able to replace the capacitor with a new 0.47 uF cap. After returning to the car and installing everything i was somewhat surprised to see no response from the unit at all. I'm not sure if i damaged the board to the point of no return, or i used the incorrect size Cap. or if it was installed incorrectly (polarity wise) . My only choice that i see at this time is to try and remove the cap and install it in the other direction with the thinking that the polarity is incorrect. If that didn't work I’m sure that i probably damaged the electrical board.
If anyone has some ideas i need them, trying not to spend $250.00 to buy a whole new unit.

[Silverevo]

my heater works then stops working and back and forth. if i let the car sit for a while it will work again. all buttons are functional and light up but no air blows....would that be the relay or blower motor?

[BMWManiac]

Everything works, but when the air goes through the "toward person" vents, there is an awful, load audible noise/click

[Cyrix2k]

I fixed my climate control about a week ago. It only displayed symptoms for about three days before I tore it apart and replaced the cap. I was lazy and didn't feel like buying the correct cap, so I tried a .1uf tantalum cap which failed to work. I desoldered that one then returned to my car with the circuit board & a myriad of caps and simply tried each cap with the ignition in run. I found that a 10uf electrolytic works great - and oddly enough, it works regardless of polarity.

[cheweez78]

dam, i just typed a long message. i received an error stating that i don't have permission to post SMILEY's. than i lost all my message. doh!

i just replaced my capacitor yesterday. My total cost was a little over $20, the actual capacitor was $1.29. Radioshack didn't have any so i had to buy it from fry's. this diy saved me over $280, my independent bmw mechanic quoted me for a rebuilt module of about $300

i tell you what though, it was very simple to replace the capacitor i would give it a 3 for being easy (easy 1~10 hard). i have no prior knowledge of soldering, this was my first solder.

Symptom:
control module shutoff completely (dead). than after restarting the car it came back on. while driving yesterday the control module became possessed and must've shutoff and on at least 10 times before it stayed on for the rest of the trip on. 100miles later it's still working. I'll keep yall posted on the progress...

Great post, thanks!

[Toddlovesm3s]

I'm having similar problems with my unit randomly shutting on and off. Also, sometimes the backlight shuts off but the lights behind the buttons stay illuminated.....pressing buttons does nothing when this happens but it usually only lasts for a minute or so. I've been living with this issue for the past 3 months dreading the thought of having to buy a new unit. I'm gonna try replacing the cap this weekend. Should be an interesting way to learn how to solder. Great info btw

[CIVILIZD]

hey people i just had some great success! unit was shutting on and off at random and i finally replaced the capacitor for $1.99 and it worked great! it was really easy and simple thanks to this great link>>>>> http://www.macadamizer.com/bmwfix.html

[kerdener]

I had this problem with my M3 in February, ended up doing the capacitor replacement and it's been a champ since. I live in Texas, so we're well into a/c weather already, and I've had no problems for ~3 months. ;)

I hobbled along for a while before attempting the repair, and saw most of the symptoms that others have described above - buttons unresponsive, screen turns off, blower turns off / on by itself, can't shut it off sometimes, can't turn it on other times.

If anyone else is having problems like this, definitely give it a shot. There are a couple gotchas, but mostly minor, and once you get into it you'll see how easy the repair is.

If you'd rather order a replacement climate control unit altogether, you can order a BMW OEM replacement from Pelican Parts for $368 (part # 64-11-8-378-466-M9) or a rebuilt unit (rebuilt by Programa) for $221 (part # 64-11-8-378-466-M250). Both of these options are probably less than your $tealership will charge...

[BKarre]

Will resoldering the capacitor help cure issues of the fan itself turning off? My unit lights up properly (maybe died a couple times) but the fan almost never works. I'm wondering if this is the blower resistor, or perhaps the blower motor, but if the capacitor will fix these sympoms that'd be great.

[gilly]

If replacing the capaciter doesn't work for you try this guy:

http://cgi.ebay.com/ebaymotors/BMW-CLIMATE-CONTROL-REPAIR-REBUILD-E36-FIX-318-323-328_W0QQcmdZViewItemQQcategoryZ33545QQihZ017QQitem Z270081347908QQrdZ1QQsspagenameZWDVW

[mikea128]

If replacing the capaciter doesn't work for you try this guy:

http://cgi.ebay.com/ebaymotors/BMW-CLIMATE-CONTROL-REPAIR-REBUILD-E36-FIX-318-323-328_W0QQcmdZViewItemQQcategoryZ33545QQihZ017QQitem Z270081347908QQrdZ1QQsspagenameZWDVW

$5 says that guys just replaces the cap...although he may be better at soldering than most of us.

[BKarre]

Does the capacitor have anything to do with the blower not working?

[gilly]

$5 says that guys just replaces the cap...although he may be better at soldering than most of us.

Very true. That might be all he does. Whatever he did worked well for me. I might have paid $40 for a $2 capacitor but lesson learned :stickoutt I wish there was this right up about changing capacitors when I was in the need of a fix. :rolleyes

[mikea128]

Does the capacitor have anything to do with the blower not working?
the capacitor is the issue with the climate controller being unresponsive. if you're climate controls appear to work, but the blower doesn't, then it's a different issue.

[Bolidoendiablad]

Just wanted to add myself to the looong suffering list of people with this problem.
IMHO the capacitor might well be the solution for all or most of the symptoms described by other owners. It will be interesting to know where this capacitor is acting to cause these problems.
If I look at my own unit - which goes on and off many times until it stays on, have the lights on but nothing seems to work, etc- it really make sense because it almost act like it doesn't get the proper amount of juice to work properly, hence the generalized failure.

I'm sure there is a lot of people more versed than myself in this matter - which can also correct me if I'm wrong - but as far as I know , the capacitor accumulates current to be delivered at a certain time ( determined by the faradays - or capacity) or accumulates this current all together to be delivered to the next component in a particular way or something like this; but if this is happening at an early stage on the circuit board, then it make sense that could alter many different functions of the unit. Opposed to a failing component ( cap, resistor, diode, etc ) that only concerns an individual function ( like fan speed ) at, what I'm going to call now, a late stage in the circuit board.

Electronics engineers...... Please forgive me:rolleyes, but I tried to explain my point of view the best I could and pushing one of you to bring more light to this and hopefully be able to determine the right capacity and voltage for that fella.

[ZoomZoom951]

Can anybody please tell me exactly what capacitor is needed (uf), and what polarity.. Thank you.

[Bolidoendiablad]

bump

[jetmech3421]

I have to chime in on this one only because I've had intermittent climate control problems on both my 97 M3, my wife's 98 328iC and my sister's 328iC. I all three cases, resoldering the capacitor only, and not replacing it, solved the problem.

From my own experience, I would replace the capacitor as a last resort. Getting it out of the circuit board can be a real pain. The conductor material on the board at one of the capacitor legs is very very small and is easily damaged in the process of removing the capacitor.

Three cars + three resolder jobs + three fixed climate control problems = resolder the capacitor first!!!!

[AMDdude]

My issue: everything works as it should, CC lights, buttons work perfect..however it takes a long time for the blower to engage, once it starts blowing air everything works perfect, until the next time I turn off my car and restart it, the blower is not working again for a long time..than all of a sudden it will start again..this seems to be related to temperature. the colder it is the longer it takes for the blower to kick in. I've already replaced the FSU and still the same symptoms...what should I do next the Blower Relay or the Capacitor?

[AMDdude]

Fixed my problem! It was a bad blower relay..the baby blue relay #9 all I had to do was clean it on the inside, but may as well buy a new one. Yes I get Ac/heat again!!!

[adnanm3]

i fixed this issue on my first e36 years ago...now on my new one the obc wont slide out for some reason...
when i put my finger up the sunglass holder space, the OBC wont budge
no matter how hard i press, seems lik im moving the dash of the entire car
any ideas?

[David_L]

Mine just went out today. Looks like I'm going to have to solder that little booger in. Wish me luck :(
Its fookin hot down here!!!

[David_L]

Well I did this and it worked!
http://www.macadamizer.com/bmwfix.html
The smallest amount of caps I could find was 2000 of them as fry's didnt seem to stock this cap anymore. If anybody needs one or two let me know and I will ship. I have 1999 to get rid of :D

[M3Jokster]

this is an awesome writeup..thanks...

my fan motor just crapped out..will be checking the fuse and relay tomorrow..
worked this morning...but this evening it died.

btw..i have a 95..so it's manual not digial.

[imstimpy]

The description of a baby blue relay doesn't work for my 99M3. There are non with that description. I think I have isolated the relay in fuse panel relay position #9 in the Bentley diagram. The dealer is useless since their diagrams reference relays by color and pin orientation, not functionality.

The position #9 is described as "White Green" by realoem.com. With that relay pulled, my fans do not work. With it installed, they work. I'm going to replace it. The part number for the blower relay on a MY99 M3 is 61-36-8-373-700.

[rmn]

Does anyone else have this issue:
Whenever I turn my car on the blower will be on the lowest setting. It doesn't matter if when I turned my car off the blower was off or on high or any other setting. It remembers all the other settings (air conditioner, defrost, etc) but always defaults to the fan on the lowest setting.