Heater fan inop

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maybeillbuyit
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Heater fan inop

Post by maybeillbuyit » Sun Apr 21, 2019 1:05 am

The heater and AC fans dont work in my 77 530i. It worked a bit when I first got the car but now that the car is operational the fan doesn't do anything. Electrical diagnosis is really my weakest skill. I've read Peters excellent write up in the FAQs for the heater fan control re&re to get rid of the sticky gummy control ring issues. But my control ring spins nice and smoothly so I'm thinking it may be something else. I don't see anywhere on the forum or web anything about a resistor like the e28 has, is there one on the e12? Or maybe some other well known problem that may affect the blower motors function? I suppose it could be the control ring needing to be dismantled and cleaned but I thought I'd ask here first before tackling that. Thx Dave . All the fuses are in good shape and none are blown
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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528i-1981
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Re: Heater fan inop

Post by 528i-1981 » Mon Apr 22, 2019 2:39 pm

Hi Dave - maybe this will help, maybe not. Electrical gremlins have myriad causes. The center console plug (8 pins I think, it also connects to the rear defogger switch) has a green wire with a brown stripe that brings power to the blower motor (that's the way it is on the 81 528, and I assume the same for you). I believe that the dial control with the clock changes the resistance through the ground, and that's how you get different speeds with the blower. If you can probe that GRBR wire (with the key on) against ground and get a voltage (12V) then at least you know the blower is getting power, and therefore that the ground is the problem ... and therefore likely the dial control will likely be involved. If you don't get a voltage, well then maybe it's a loose connection or a problem in the fuse box. That part of the circuit is very simple on the schematic. Good luck!
(oo=00=oo) Eric
1981 528i Manual

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maybeillbuyit
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Re: Heater fan inop

Post by maybeillbuyit » Thu Apr 25, 2019 12:41 am

OK thx for the tip Eric. I'm sure I probably need to just remove the whole unit and clean the rotating dial properly.
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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Mike W.
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Re: Heater fan inop

Post by Mike W. » Thu Apr 25, 2019 10:35 pm

It's a pain in the ass to take apart the console at all. So start by checking for voltage and ground, which should change, at the motor wires themselves. Usually they die by wear and rattle and squeal, but I've seen them die silent deaths too and just not work.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

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maybeillbuyit
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Re: Heater fan inop

Post by maybeillbuyit » Sat Apr 27, 2019 9:04 pm

Hey thx Mike, I know you’ve worked on these dials and fans a lot. I appreciate the input. Im hoping since it did seem to work a bit its maybe just corrosion on a connection or something simple. I’ll report back when I get into it.
Dave
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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maybeillbuyit
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Re: Heater fan inop

Post by maybeillbuyit » Mon May 13, 2019 7:01 pm

OK well I've been working on this issue today with not much success. So far I have power at the fuse that supplies the blower motor. No power at the the two wires that supply the blower motor. I disassembled the console and mostly pulled out the center console holding the center console plug as the rotary dial is called. There is power to it which I kind of knew because the clock works fine. I've also removed the fan motor assembly and tested it and the motors spins fast on just straight 12 volt from the battery. I thought at first I was looking for a heating/cooling relay but I didn't find one in there and realized I was using a BMW electrical trouble shooting manual for a 1977 630csi which apparently has a relay but my doesn't seem to :oops: I've also been using the Haynes electrical schematic for the 1977 model car and it doesn't seem correct at all. Its got more wires and different colored wires than my car has so I've given up on that. I thought there was a link to a bunch of manuals on here some where. Anyone know where that is? On the bright side I didn't find pulling the whole console apart as bad as I was expecting although maybe putting it all back won't be much fun. Pics later when I have time.
After more searching and pondering I found another separate schematic in the Haynes manual for 1977 530i's with AC which my car has, like the BMW 630sci Manual it shows a relay so maybe I do have a relay in there somewhere. Anyone have any insight where it is? I know the later cars (81 e12s) have a relay for the fan motor just below the rotary fan speed dial. I don't have one there so Im kind of stumped. Also none of my wires are the same colors as either of the schematics. Weird
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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maybeillbuyit
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Re: Heater fan inop

Post by maybeillbuyit » Wed May 15, 2019 10:26 am

528i-1981 wrote:
Mon Apr 22, 2019 2:39 pm
Electrical gremlins have myriad causes. The center console plug (8 pins I think, it also connects to the rear defogger switch) has a green wire with a brown stripe that brings power to the blower motor (that's the way it is on the 81 528, and I assume the same for you). I believe that the dial control with the clock changes the resistance through the ground, and that's how you get different speeds with the blower.
I just reread this and my center console plug is quite different than the later plugs. Mine only has 4 wires, black, blue, yellow and brown (ground) . It doesn't match the schematic I have at all. I can see where the red/white wire supplies power to the clock but no power seems to come to or leave the center console plug. And theres no relay anywhere. Totally confused here.
I've taken the center console plug apart and its perfectly clean with what looks like new grease in it so its not like its all gummed up like I know they can be.
More searching today. WTF have they hidden the relay :shock:

So going over Peters heater switch refurb page on the FAQs I notice that the back side of the center console where the heater control is has attached to it from left to right . Relay, therostat, and micro switch with my car has none of. I have figured out that even though my car is a MY 77 its actually a 76 model with a very different system than the later 77 and on models. Question is where is the relay etc?
Image
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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maybeillbuyit
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Re: Heater fan inop

Post by maybeillbuyit » Mon Jun 10, 2019 11:51 am

OK after taking apart the dash console and pondering all this I found the heater fan in ggod shape , it works fine just hooked up to the battery. I got a correct BMW electrical trouble shooting manual for this model car instead of the manual for the 630i which was completely different. I assumed it would be similar but it wasn't. Lesson learned. Really a great book to have I'm sure its available online but I couldn't find it anywhere.
ImageIMG_6307 by Dave Grayson, on Flickr

Heres the schematic for the the fans etc. You can see there isn't a relay involved in this system so that explains why I couldn't find one. So this years model never used a relay but all later cars seemed too. And the resistor in the diagram is nowhere to be found but I assume its buried in the AC blower box. Really a convenient place to hide it. Luckily I haven't needed to dig that out.

ImageIMG_6308 by Dave Grayson, on Flickr
ImageIMG_6309 by Dave Grayson, on Flickr

ImageIMG_6035 by Dave Grayson, on Flickr
As I pulled more stuff apart I found that the AC fan control switch was actually falling apart with ball bearings and springs dropping out of it. Its NLA from what I can tell. Since power is routed through both switches the broken AC switch was stopping power getting to the Heater fan switch The AC switch was all corroded inside from what looks like a past attempt at repair. Whoever fixed it last time did a horrible job soldering and it just fell apart. I put it all back together and everything seems to work fine now. Funny thing is this part seemed to be made of bakelite which seems like 50s technology. :lol:
ImageIMG_6045 by Dave Grayson, on Flickr
ImageIMG_6047 by Dave Grayson, on Flickr

After I put it all back together I used wire to hold it all together. It will make it easy to take apart if I ever need to mess with it again. The previous repair had used glue that had failed and it and crumbled apart. I'd be happy to get a spare of this , so if anyone has this switch from an early car let me know . Part no. 64511466022 . or a superseded no. 64511356020 Looks like some e21s used this switch as well
ImageIMG_6049 by Dave Grayson, on Flickr

All back together:
ImageIMG_6040 2 by Dave Grayson, on Flickr
I also took apart the rotary heater fan switch and it was in very nice shape inside. Not gunked up or worn at all. I didn't take many photos of this part but it wasn't as difficult as I was expecting and I just put it all back together
ImageIMG_6154 by Dave Grayson, on Flickr

And the AC fan works and you can hear the AC compressor click on althought I don't have a fan belt on it right now. I'm sure the system needs a recharge. Thats down the list at this point. I'm posting this for anyone who cares about the early models that are a bit different than the later cars. And I'll link to this post from my project post on the car.
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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Lock
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Re: Heater fan inop

Post by Lock » Fri Jun 14, 2019 12:38 am

This is great information, thanks. I really don't want to take my heater controls apart but I'm going to have to one day because it's getting a little gummy, so these pictures are really useful. You make it look easy.
In other cars I've fixed the fan speed resistor packs are in the airducts to keep them cool. I'd guess the same for ours.
1979 528i 5-speed conversion G260/6

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maybeillbuyit
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Re: Heater fan inop

Post by maybeillbuyit » Fri Jun 14, 2019 11:06 am

Yes I guess that makes sense to keep the resistor cool, sure make it a pain to remove thought. All in all I didn't find any of this really to hard its very time consuming kind of awkward leaning into the dash to disconnect everything. Disconnecting the two shafts that control heat and the where the air come out was a bit hard, I'm glad I had extra parts to practice on. I'll try to post a few pics of that later to make it easier to understand. It sure is nice to have everything working in there now. I wish my AC was working, its hot here now. That will have to wait though.
1977 530i another project
1979 635csi Euro "project"
1987 635csi

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