Aux fan repair & diagnosis. Fuse 18 consistently blown believe resistor bad

[somecarguy]

I have checked all the electrical connections at Relays K6, K1 and fuses 3, 18 and all is well. Tested them with ignition to on, a/c switch on/off and thermo switch wiring jumped and everything is okay including relays and voltage sent to fuses.

Fuse 18 blows instantly. Replaced with spare 30amp, blows.

From what I've read this points to the resistor, which I will order and replace. Can anyone describe the feel of a "normal" factory fan when rotating? Mine makes no noises but provides consistent, smooth yet relatively heavy resistance when rotated by hand. For instance a few fingers won't do it, you need a decent purchase on it to make it go.

Want to be sure the fan itself is not suspect.

It does not run on either low or high.

[richardodn]

Sounds like the fan and not the resistor. Normal speed runs through the resistor. High speed bypasses it. To verify, disconnect the two red wires from the resistor (They should remain connected to each other) and jumper the radiator switch from green/black to black/brown. This will energize the high speed relay. If #18 pops again it's the fan since the resistor is out of the circuit. Find your ETM here http://wedophones.com/BMWManualsLead.htm and look at diagram 6454-0

[Ceekers]

not an uncommon problem with aux e30 fan. The stiffen up when not in use after a few years. the fan should move freely by hand and not without any hard push required. Fan motor creating resistance causing it to overheat - blowing fuse. ellectrical fire prevention.

what you can try; unplug the fan from the harness - jump the connectors with alligator clips or a donor harness and apply direct power from another 12V power supply or your car battery; sometimes I've had luck in freeing up the fan up by running it this way. Resistor is for low speed. Even if you don't have low speed you can still operate the fan.

[somecarguy]

Thanks guys appreciate this feedback a lot. If I do need a fan, is there a recommended factory replacement that bolts right up and doesn't need any add'l controllers etc?

[Ceekers]

The resistor is designed to run on low when the demand for max cooling isn't necessary. you could by-pass the resistor to only run on high. You would need to run a direct power supply to the fan via a switch inside the car. There are other aftermarket fans out there but I am not for certain whether they are dual speed fans.

[Jeffnhiscars]

A blown resistor will cause an open circuit that can't blow a fuse, so it's either your fan as has been suggested or a short. Beyond that not only do you not need 2 speeds, but lots of people jump the resistor (including me) so it runs only on high. Spal makes a good 14" pusher that fits nicely.

[somecarguy]

Appreciate this info. Does anyone have a link to a thread where someone mounted the 14" SPAL?

[somecarguy]

This Spal appears to have a number of radial mounting points. Anyone know if they mate up to the mounting points that BMW used? I wonder (hope) if these are some sort of standardized thing.

https://www.jegs.com/i/SPAL/063/3010...SABEgKJGfD_BwE

- - - Updated - - -

This appears to be the highest performance 14" pusher fan Spal makes. Now I wish I still had my old condenser to check mounting... anyone have one laying around?

https://webstore.spalusa.com/content..._2056_SPEC.pdf

[Jeffnhiscars]

I think PB killed the pics on my r3v "barn find" build thread but the fan was not hard to mount and no need to remove the valance as some will tell you. I drilled out a pop rivet on 1 and reversed the bracket, twisted another 90 degrees and dont recall the rest but it hasnt made a peep in 4 or so years. I used the Spal harness as well so the fan is PNP

[somecarguy]

I think PB killed the pics on my r3v "barn find" build thread but the fan was not hard to mount and no need to remove the valance as some will tell you. I drilled out a pop rivet on 1 and reversed the bracket, twisted another 90 degrees and dont recall the rest but it hasnt made a peep in 4 or so years. I used the Spal harness as well so the fan is PNP

I had the kidney off just now looking at the fan and it did seem it could come out upwards through the kidney/grills with a little bit of contortion to get the lowest fastener off.

If you happen to have the part numbers you ordered I'd appreciate it as a check, otherwise I measured the existing fan and it seems like it ought to work with the one I posted, which is the highest capacity SPAL makes in a 14".

[Jeffnhiscars]

I changed fans out the bottom. gL trying it the other way

[somecarguy]

Ha I will need to take a closer look. Does the oil cooler get unbolted for that?

[Jeffnhiscars]

Ha I will need to take a closer look. Does the oil cooler get unbolted for that?

I don't recall

[somecarguy]

Replacing the resistor and the wiring terminals solved this problem. The resister crumbled when I removed it and there was corrosion evident on the exposed ring terminals. I replaced them with new ones. Molex total seal would have been ideal and is really what the factory should have used in this low, wet area but all I had were uninsulated terminals so I heat shrunk them and covered the exposed ends with dielectric grease.

When I was testing things prior to re-installing the resister it almost felt as though the fan needed a “jumpstart”. tapping the two red terminals together seem to free the fan up and then it spun very nicely did not blow the fuse and now spins easily with finger pressure.

Since the low and high speeds are both wired with 12ga I do not see what the problem would be with replacing fuse number three with a 30 amp and then omitting the resister. According to the wiring diagram there would be no apparent bottleneck in conductor size but I am not positive what happens inside the relay and fuse block. Regardless I will try it wired as the factory intended and see how it performs.
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[RomeoMike]

^ Congrats on needing to do less. I pulled the aux fan from the 90 vert with oil cooler recently. Went more or less according to the book (draining/removing the radiator; undoing the two condenser bracket bolts once the radiator is gone), did not have to remove the oil cooler but it certainly gets in the way. The lowest mounting nut on the aux fan is the biggest pain to access. Put some bungee cords in the condenser bracket to hold it up so I could use an 8mm ratchet on the lower nut. Pulled the fan out through the engine bay.