Yes, Thank you OP. I did this about a month ago. Lifesaver!
Thanks again for this site. Had the same issue happen yesterday and was scheduling an appt today to get it looked at. Now I will try this myself when I get home!
Anyone have decent closeups of the working side of the resistor pack?
On the E28 series cars - there was a relay like contact set on the resistor pack that connected power to all three resistors (full-speed, ie - 4 - is straight through, no resistor used.) This contact was held shut by being soldered together with "Woods Metal" (a low temperature solder.)
If the airflow was completely shut off on an E28 (and it was possible) or the intake was blocked - the resistors would start to overheat due to no air flowing over them, and rather than have a fire - the Woods Metal would melt, disconnecting power to the 1-2-3 speed resistors.
Fix for that one was simply to heat up the contacts with a soldering iron and press them back together. They'd stick together again if heated right, and the broken relay pack became a working relay back.
From the description people are giving about a "telegraph key" sort of thing, I suspect this resistor pack uses the same safety feature - and if you lost 1-2-3 speeds but still had full-speed, it's the safety contacts that have opened.
So need a picture.. or two..
Don Eilenberger
'01 M-Coupe, '03 525iaT, '07 R1200R
'06 Porsche Cayenne S - Titanium Edition (Iceland silver/Titanium
Followed these instruction last week (Thanks!). Just pulled out the resistor pack and cleaned the contacts with WD40 and a small wire brush... There were no signs of melting at all and all speeds work again. The pack seems pretty simple-the resistors are just coils of wire in various sizes.
I bought the resistor, but mine started working again of its own accord. I therefore have one spare resistor. It's new in box. If anyone needs one pm me.
Alpine White 2005 325i
I have attached a jpeg of the blower switch/resistor pack wiring with a little extra labeling.
As you can see, the voltage to the blower motor is dropped across all three resistors in switch position 1, two resistors in position 2 and one resistor in position 3. Also note that there is a thermal cutout in series with the resistors that ONLY interrupts power to the blower in the first three positions.
If the blower motor only operates in position 4, the culprit is most likely the thermal cutout (OR the contacts for the pack in general), but it could be the last resistor before the cutout as well.
The trick of reheating the contacts of the cutout with a soldering iron while holding them together should work, but I would caution against adding any solder just in case they selected a material with a specific melting point.
It's a shame that they didn't use a bi-metal contact. Then it would pull away when it got too hot and reset itself after it cooled back down.
Dennis
Yup - same design as the E28 one. Google "Woods Metal" - very commonly used for this sort of safety device, as well as the meltable plugs in sprinkler heads.
Ah - found it. 158F melting point: http://en.wikipedia.org/wiki/Wood%27s_metal
I actually have a bar of it somewhere..
The bi-metalic contact would be nice for resetting, but I'm guessing they assume they don't want the resistors repeatedly overheating if the obstruction to the air flow isn't removed.
It's a shame that they didn't use a bi-metal contact. Then it would pull away when it got too hot and reset itself after it cooled back down.
Dennis
The dumb part on BMW's part was - you could shut off all air-flow quite easily with the sliders on the E28 heater. MANY of these failed due to the design. At least on the Z3/M-series you can't cut off all the airflow without some serious intent (put it on face level then close ALL the face level vents is about the only way I see to do it.)
Don Eilenberger
'01 M-Coupe, '03 525iaT, '07 R1200R
'06 Porsche Cayenne S - Titanium Edition (Iceland silver/Titanium
Thanks bcausseaux! After reading your DIY, I did this job on our Coupe. The wiper arms were stuck tight. I didn’t want to go out for a puller so I tried my electric heat gun. I set it on low and pointed it straight down at the shaft while I jiggled the base of the arm. The arms popped off in about 30 seconds.
The other minor issue I had was with the sealer that’s between the plastic panel and the windshield. Mine was in bad shape so I cleaned it up and applied 3M Strip Caulk. Problem is the next time it’s taken apart, the 3M stuff will be a mess to deal with. I need a better idea.
Excellent write up! Of course my fan resistor goes bad right after I read it... and was a nice and easy fix!
Thanks!!
-Joe p.
Amazingly, as I was attempting this fix and went to the dealer to purchase a new resister pack, the parts guy suggested to clean the contacts with a little sand paper and then contact cleaner (the part where the "telegraph thingy is", and not to purchase a new one. Low and behold, it worked great!
Ugh...I just had this issue. Tore it apart, cleaned it, put the resistor pack back in there, checked it, YAY! it works. Buttoned it all back up and took it out for date night. DAMN. It was only working on 4 again.
Guess I'll have to buy a new one. At least I got my practice taking the 20 clips out.
Part#- 64116912633
Last edited by Car54; 08-30-2010 at 10:53 PM.
Craig BricknerClick to Join: BMWCCA # 366493
BMW CCA/PBOC/Chin Motorsports DE Instructor
2008 M3 Sedan Jerez/Black
I can't believe this write up still gets hit four years after I wrote it.
I don't know, but I think this deserves a
Thanks for this!
What's surprising is the number of people who just don't understand that the "contacts" are actually a fuseable link. Cleaning and sanding them is very nice, but it's not what will make it work reliably. Heating it up (soldering iron) and pressing them together is what WILL - since the contacts will once again be bonded with the Woods Metal that was used originally.
Don Eilenberger
'01 M-Coupe, '03 525iaT, '07 R1200R
'06 Porsche Cayenne S - Titanium Edition (Iceland silver/Titanium
Thanks for the detail write up...its been ten years of ownership and sooner or later this is gonna happen to me...
I know this is an old thread but it's never too late to say "Thanks"!
I still have a spare resistor. It's new in box. If anyone needs one pm me.
Alpine White 2005 325i
I need a resistor for my Z3m. Don't know if this is how you PM.
I replaced the resistor on mine following the instructions, works great now. Tried cleaning the old one but it did not help. The wiper blades were a pain but I got them off after a few tries. Thanks for the write up.
It's already been said but apparently nobody reads this part :
YOU HAVE TO RESOLDER THE FUSE IN ORDER TO GET YOUR RESISTOR PACK TO WORK AGAIN !!!
I resoldered the connections to the resistors. They are only crimped on and with my ohm meter I could see what the problem was by measuring. I resoldered all off the connectors and all is well now.
Hi folks,
I'm trying to troubleshoot why my blower fuse (30amp #20) on 1998 M Roadster keeps blowing out. I replaced the fan switch ($80) and tested the blower motor with inline 20amp fuse and it works fine. However, when only the blower is operating (no AC or recircle on), the fuse blows as I'm switching from 3 to2 or 2 to 1. It happens after about 1 min of operation. I'm not sure these threads are relevant, but maybe someone knows my problem?
Thanks,
Leon
Bookmarks