Radiator Fan

[ahebron]

As part of the rebuild on my '95 318 ti auto I have discovered that the low speed radiator fan resistor has gone west. I removed the resistor and sliced it open to find out what is inside. Lots of silica sand, a wire wound resistor on a ceramic former and what I thought is a diode. The alleged diode is open circuit both ways so I cannot get a reading on it but it is bullet shaped silver colour 12mm long 5mm diameter with a red tip. I have replaced the resistor with a couple I bought from the local computer wrecker but this other 'thing' has got me buggered as to what it is. Anyone got any ideas?

Thanks
Adrian

[cali-ti]

you must be the chap that posted on the yahoo list :) did the resistors along fix the issue or not? any pics we could look at?

[ahebron]

Yep thats me, I don't know how many of us are on both lists. The resistors work fine but Iwant to know what this bloody thing is and if I can or can't do with out it. I have placed a photo at
http://www.318ti.org/gallery/showphoto.php?photo=1987&cat=530

Thanks
Adrian

[cali-ti]

i would make sure to post a link to the pic on the yahoo list. i have no clue what that thing is :)

[cossieturbo]

1st thing I would have pegged that for is a Resistor, but I'm guessing a Cap. I'll be right back...

cripes... the wiring diagrams give up nothing. Odd though that the 1995 shows no Motor Resistor while the 1996 does...?!?!

the pic looks as though it is a ceramic Resistor that is covered by an Aluminum can while just showing one Color Band. I'll post back if I find out. I'm curious now...

cossieturbo

[ahebron]

If that bit alone is a resistor I would be very surprised as it is too small for the current draw. I would have said capacitor too but it appears to be in series with the resistor and again I would reckon too small. My Haynes manual is hopeless for wiring diagrams and my BMW electrical cd doen't cover the E36 range.

Thanks
Adrian

[cali-ti]

given the hint from gerry doiron (sp?) from the yahoo list, i started searching for something that looked like what you posted. i believe he's right (that list is scary knowledgeable):
http://content.honeywell.com/sensing/prodinfo/thermalfuses/RediTemp_TCO.asp

http://content.honeywell.com/sensing/prodinfo/thermalfuses/images/thermal_cutoffs_rtemp_lg.jpg

[ahebron]

Thanks, that looks like the bugger. Funny thing is the thought that it was one of those briefly flicked through my mind. But the fact that it is totally unaccessable when it needs replacing meant that I dismissed it.
Damn those Germans are crafty.
So its down to the electronics shop and pick one up. I will mount it in such a way that if it happens again it wil be an easy job to replace. The sad thing of all this is I am a registered electrician. ;>(

[cali-ti]

once you get everything sourced, it would be GREAT to have all the needed bits and values in a KB article for the future. this damn resistor pack seems to be something that fails often enough to be annoying (and you can't get a stock replacement from bmw).

[ahebron]

I have decided to give it a go with out the thermal fuse. It seems to be more of a hinderance than a help. I picked up 2 x 1.5 ohm 50 watt resistors from the local computer wrecker for NZ$1.00 each, these are sealed in a finned aluminium housing so they have their own heat sink. I have wired them in parallel to get the required resistance and covered the soldered joints with heat shrink. Luclily the resistors are close to the diameter of the old resistor tube so they will clip into the old mounts with a section cut out of the fan shroud to let the bottom resistor have enough space.
All I need to do now is get the car going to test out my fix. I will keep you all posted

[aceyx]

It is most definitely a thermal fuse. Wish I had seen this earlier, I could have pointed it out.

The only problem is that there's no temperature rating on the fuse; normally it is stamped on the cylinder. Once the fuse is blown, I'm not sure there's a way to test the melting point.

Sadly, the color doesn't say much either as it's just whatever epoxy the company uses.