Help: Aux fan magna resistor, What is the resistance? - BMW Forum

Rfitz25 · 07-26-2007, 06:42 PM

I have the magna style not the Bosch style.

Anyone know what the resistance rating is supposed to be so I can replace it cheap not the $40 replacement?

I read a post once from someone that did this and it worked fine.

I think I can get the right aluminum cased spun resistor part cheap, I just need to know the ohms needed.

I'm going to be replacing the brocken fan with a used one and want to throw in a new risistor while I'm at it.

Summer heat!! San Diego.

Thanks in advance

StarMavin??

Starmavin · 07-27-2007, 09:02 AM

I can't seem to find any values on the magna style. The magna and the bosch don't interchange so the bosch values won't help you.

BMWJNKY · 07-30-2007, 12:56 AM

Get one from Pick-n-Pull or don't go out to dinner a few times and just buy a new one.

Rfitz25 · 07-31-2007, 04:31 PM

Are the Bosh and Magna style different ratings or just different wiring connectors?

Whats the Bosch rating anyway if you have it handy?

I believe my existing one is still good I just wanted to put a new resistor in when I replace the fan with a clean used fan, which I havent found yet.

I can get a nice clean aluminum cased finned resistor cheap that should do the job.

Starmavin · 07-31-2007, 09:20 PM

The bosch is around .3 to .5 ohms at 85 watts. The bosch uses a resistor wire where as the magna brand uses a magnetic style ballast resistor. Often times the glue lets the magnets loosen up and fall out of place then it can't transfer the volts. They "can" be fixed but more times than not you'll end up destroying it trying to get it open.

Rfitz25 · 08-12-2007, 04:35 PM

Bump LOL

Questions:
It was payday fri so I'm close to going to the boneyard for a used aux fan.

However:
I spin the main cooling fan when its hot and it still spins freely??? Is is bad??? Looks good no oil leak? Shouldnt the fan clutch kick in when its hot and be hard to spin? (of course I do this without motor running)

Maybe I'll do the clutch at the same time as aux fan but hate to replace good parts?

In the mean time I'll race my virtual BMW M3 GTR on Forza motorsports Live LOL
as well as my BMW V12 LMR and McLaren F1 BMW

Starmavin · 08-12-2007, 09:53 PM

Sounds like the fan clutch is shot.

Rfitz25 · 08-15-2007, 01:46 PM

Not so sure now.

I did the magazine/newspaper fan clutch test when I got home last night, it was all warmed up, I used a good cardboard paper towel tube (read in some other posts) and tried really hard but I couldnt stop the fan. Seems like the clutch was well engaged.

Maybe it only fails at really high temp like at the last autox.

Found a new aux fan at local inter auto parts $185 but its the bosch ceramic resistor and fan blades arent attached to the outer ring like mine is and the wire conneector is much shorter so I'm not going to buy it? The pic from bavauto is like the one I have? I'll keep searching. LOL
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