E34 blower problem and don't think its the sword

[ck1995]

1990 525 w/ the sword for the blower control. My blower stopped working about 6 months ago, after visiting E34 website I pulled out sword and cleaned it. Fixed my problem............so I thought. The other day fan wasn't blowing on lower speeds, cranked it to 4 and it worked then stopped then worked again. Continued the rest of day off and on, next day it stopped working all together. Does this sound like sword problem or something else. Any help would be greatly appreciated

[pundit]

1990 525 w/ the sword for the blower control. My blower stopped working about 6 months ago, after visiting E34 website I pulled out sword and cleaned it. Fixed my problem............so I thought. The other day fan wasn't blowing on lower speeds, cranked it to 4 and it worked then stopped then worked again. Continued the rest of day off and on, next day it stopped working all together. Does this sound like sword problem or something else. Any help would be greatly appreciated
I'm not sure what you mean by cleaning it?

However check this thread...

http://www.bimmernut.com/forum/electronics-lights-plus-c/9641-fixed-my-sword-fan-speed-controller.html

The other possibilty is cracked solder joint where the connector socket is attached to the PCB. This can cause intermittent operation. Try removing the sword, then plug it in and the switch on the fan and gently flex the sword PCB as well as pressing on the various components (including the connector) that are soldered to the PCB. See if you can cause the intermittent operation you have been experiencing by doing this. It then should be possible to isolate the cause.

Good Luck - pundit

[ck1995]

What I was referring to with the cleaning is What I guess you'd call the blade portion of the sword. I guess it was just dirty after almost 15 years, I cleaned the blade and the exterior connections w/ alcohol.

Appreciate the tip on checking the connections, sounds good and will try it out!

[JonE]

Sounds like you'll need a new sword to me. If the only fan position that works, even intermittently is "4" or high then the sword has likely failed. Mine even worked intermittently on 1,2,3 but always on 4. As soon as I replaced it, no more problems.
But, good luck anyway!

[ck1995]

Electronic question. I pulled apart the sword as described above and all connections seem good. I have no idea what the piece is called that is wrapped in copper wire and has a moveable part w/a spring attached but that is where my problem is. By manually moving this piece it created a tiny spark and the fan works. Right now it operates but if I turn blower off sometimes it will come back and sometimes not. Can get it going manually again everytime. Is there any way to repair this piece? I wouldn't even rate myself as a novice in this area so I don't know if I need a new sword or if this piece can be repaired?

[pundit]

Electronic question. I pulled apart the sword as described above and all connections seem good. I have no idea what the piece is called that is wrapped in copper wire and has a moveable part w/a spring attached but that is where my problem is. By manually moving this piece it created a tiny spark and the fan works. Right now it operates but if I turn blower off sometimes it will come back and sometimes not. Can get it going manually again everytime. Is there any way to repair this piece? I wouldn't even rate myself as a novice in this area so I don't know if I need a new sword or if this piece can be repaired?
The thing you refer to is called a relay. (bottom right of picture)

http://clients.net2000.com.au/~rowmat/BMW/sword_pcb.jpg

It is an electromechanical switch. It may have dirty contacts (these are located where the spark occurs) or some other part of the circuit maybe causing the fault. If you can see the relay operate but sometimes the fan doesn't start then I would suspect dirty relay contacts. However if the relay switch contacts are fine and the voltage supply and earthing is okay then simply manually forcing the relay to close will make the fan operate anyway even if the circuit that controls the relay is faulty.

Of course it could also be the fan motor itself, tight or seized bearings etc.

[ck1995]

If its just dirty relays, what's the best way to correct? Alcohol pad maybe? If that doesn't do it is a new sword the answer. I don't think it is the fan motor as it runs strong as ever. BTW I have turned the car and blower off about 6 or 7 times since I manually operated the switch but I don't think I fixed anything yet and thus left the dash apart as I know as soon as I put her back together it will stop working on me again. \
P.S. Thanks for all your insight pundit