BMW Climate Control Failure
Last week my climate control unit in my bimmer gave out. Initially I thought it was the computer shutting the thing down because the compressor failed or something, but the engine check showed a-ok. After googling my issue for a bit, I discovered that others were experiencing this problem around the 100k mile marker. It turns out that supposedly a capacitor failure in the climate control computer (located directly beneath the radio for those of you with an E36 series BMW) is at fault for this. His very detailed and accurate instructions let me fix what would have been a $600 replacement at the dealer for $.50 at the local electronics store (in my case Fry’s Electronics) and 2 hours of work.
I picked up the capacitor, removed the one detailed in the howto guide, and replaced it with the new one. Two notes I’d like to add: polarity does matter! So when replacing the capacitor, be sure to sodder the new one in with polarity directed the same way as the old one. You will need a volt-meter to test for polarity using the resistance (ohm) settings by switching the contacts of the voltmeter around when testing the capacitor. One way will result in a connection, the other way will not.
Also, another note: I succesfully used the capacitor that was mentioned in the how-to guide (.47uF50), however, the capacitor that I removed was a (u47F63). The guide mentions that there may be many capacitors that work, and I stuck to the one in the guide, since everyone has reported success with it. So far I have not had any problems.
Thanks, Richard Swope, for you most excellent guide!
[Edit: 8/5/2005 17:23 | Original Post: 7/5/2005 10:06]
I have been experiencing intermitent climate control failures after installing the new capacitor. However, my initial thoughts were that there was a cold sodder contact point, meaning that when I soddered the capacitor, it did not make sufficient contact with the contact on the board, and it cooled without gaining proper contact, leading to an intermittent or even failing electrical connection.
I had initially installed the capacitor by soddering it from the bottom, where one would expect the contacts to be. However, after taking it out and resoddering it, it appears the contacts are on the “upper” side of the board, so when you apply sodder, do it from the top, not the bottom.
After completing this “fix” it seems to be working fine so far. I’ll keep an eye on it and report on any further issues I may find.
January 2nd, 2006 at 2:54 pm
Hey there.What can I say but a huge THANKS.
Thanks for the instructions on the BMW climate control repair.I have just followed the step by step instructions and had the repair done in a little over 3/4 hour.No problems, it all works fine.Now you can add New Zeland to the list
January 2nd, 2006 at 3:04 pm
Cheers! I’m glad this helped you out.
Keep me posted if you have any issues.
February 3rd, 2006 at 4:56 am
Hi Mike,
LIke yourself I am axperiencing the same problem with my BMW. Will swop the capacitor tomorrow as per Richard’s excellent set of instructions. I do however have vital information for Richard. Tantalum caps like the one he fitted are normally polarized. There is a 50 50 change of fitting it the wrong way around. A tantalem fitted the wrong way around will work. But will fail after a month or so!!!
I am in electronics and shall determine the correct fitment polarity of the cap and would love to email Richard so that I can thank him and inform him of the correct procedure of desoldering and replacing the cap. Others would also find this of benefit.
Kind regards, Pine
February 8th, 2006 at 10:07 pm
Did you figure out the polarity? I am about to do the same thing on my E36 318.
Thanks,
Ro
February 8th, 2006 at 11:16 pm
Actually I haven’t had a problem with the polarity with my install. If I recall correctly, the thing wouldn’t even turn on if the polarity was wrong; so it will be pretty clear from the start.
I had to go back and resodder it about 3 times:
a) bad polarity.
b) cold sodder (remember to sodder from the top, not the back of the board).
c) third time’s a charm!
Let me know if you run into any troubles.
Mike
April 13th, 2006 at 8:27 am
Fantastic result. It took me 1 hour and cost £0.41 !!! Garage wanted £300.00 !!
October 22nd, 2006 at 11:21 pm
i done this fix, work’s fine but after a month, the fan increase button, stops working and the right side temp increase button dont work,it starts working when the unit get’s a bit warm?
February 11th, 2007 at 7:37 am
Thanks for the fix. We just purchased a 97′ 328i and noticed right away the problem. We found a place on the internet that we could get it repaired for $50 plus shipping both ways. I decided to try the fix and spent only $ 1.19 at the local Radio Shack.
Thanks again,
Jeff - Alabama
May 14th, 2007 at 3:17 am
Hi,
I also followed Richard’s guide and it was a great help, saved me lots of time and fixed the problem.
However, a note on the capcitor, u47 means it is a 0.47 uF capacitor, not 47uF, the ‘u’ takes the place of the decimal point, it’s an old naming convention.
As a general rule capacitors bigger than about 1 uF tend to be polarised. This is simply because it’s not practical to make large valued non polarised capacitors.
The original capacitor is not polarised so this would seem to back up the argument.
May 27th, 2007 at 8:18 am
Many kudos to Richard for taking the time and care to show exactly what has to be done. Also Mike.
However, I found that a good cleaning out of the accumulated lint of 117K miles from the fan and sensor more than likely solved the problem altho I did resolder the capacitor connections just to make sure. No new capacitor was required. An electronics expert advised that 95% of the problems he fixes just required a good cleaning.
I recommend trying that first.
‘98 328IS in New Jersey
August 6th, 2007 at 11:46 am
Thanks for the help with the fiks
Everything worked like a charm.
There, now you can add Norway to the list as well
March 31st, 2009 at 5:50 am
I had been quoted a price of $800 from my local BMW Dealer to have the control head replaced on my 97 328i. Found that the part alone was available from Bavarian Motorsports for $300, could be repaired (ad on eBay) for $49, and then found the do-it-yourself instructions. Total cost was $1.19 from Radio Shack for a 47 microfarad capacitor, part #272-1027. Time was about one hour and now everything is working perfectly. Thanks from Louisiana.