Auxiliary fan doing some weird sh*t

[Schwarz325]

So if i connected the red off the harness to the rad on the fan, why would it blow the low speed after the fan came on? the black one hit the chassis maybe? But i'm pretty sure i had it resting on a plastic piece.

Also, i think the reason they melted is because i used thin wires and i put a 30A fuse where 15 should be and the wires couldn't handle the amperage.

I'm gonna try a new 15 amp fuse and use a bigger wire on the red one.

[Schwarz325]

Oh and the temp switch plug is pretty much gone so i don't even know which wires go to which pin on the switch. I may just leave that unplugged.

[DREWHALL]

I would check out the wires going to the connector for the aux fan. Sounds like you might have something funky going on. What exactly is wrong with the switch?

Just reread I understand now. I'm not home otherwise I would look but I don't have my car or my Bentley with me.

[DaveSmed]

Oh and the temp switch plug is pretty much gone so i don't even know which wires go to which pin on the switch. I may just leave that unplugged.

If you do that, then the fan will never ever come on with just the red wire connected.

A/C affects low speed operation only. If you jump the two wires I mentioned, A/C will affect both speeds.

[Schwarz325]

By jumping them, you mean just connect them together? see the fan came on with the red connected to positive on the fan but it popped the low speed fuse

[DaveSmed]

Did the fan stop when the 15A fuse popped?

[Gnarles]

from the above diagram, the red wire is for the high speed circuit. I would hook this one up to your fan and jumper the high speed and normal speed circuits at the relays to have the fan come on when you push the ac button. The normal speed circuit is only rated for 15A, and I would bet that your fan draws more than this so you probably popped fuse 3. Hooking it up to the 30A high speed circuit will get around this problem.

I already posted a solution to your problem.

Run a wire between terminal 86 on the normal speed and high speed relays. Hook the red wire to your fan positive wire and cap off the black wire. This will activate the high speed relay when you push the a/c button.

You could have easily hooked up the temp switch in the amount of time you have spent trying to get this to work...

Using the attached connector view with hersly's diagram will tell you where the wires should go.

[Schwarz325]

Did the fan stop when the 15A fuse popped?

Yes it did.


Gnarles thanks for the clarification, i'm gonna try that too lol.

[DaveSmed]

Ok, does the red wire connect to the Black/Blue wire?


...I suspect it doesn't.

[samiam3356]

Black(SPAL) wires goes to brown

Red/Blue(SPAL) goes to black if you cut off the fan plug from the original fan and are using those wires, if using the wires before the connector it is green and black

[DaveSmed]

The low speed really needs to run through a resistor, that feed is not rated for max output current.

Cheap solution: Connect the black and black/brown wires together at the temp switch. Then connect the red and black wires together for your positive, and brown for your negative.

A/C affects low speed operation only. If you jump the two wires I mentioned, A/C will affect both speeds.

I already posted a solution to your problem.

Run a wire between terminal 86 on the normal speed and high speed relays. Hook the red wire to your fan positive wire and cap off the black wire. This will activate the high speed relay when you push the a/c button.

You could have easily hooked up the temp switch in the amount of time you have spent trying to get this to work...

Using the attached connector view with hersly's diagram will tell you where the wires should go.

All the info you need is right there.

Hook up the temp switch as follows: Connect the black and black/brown wires together. This eliminates screwing up your fuse box with jumpers and accomplishes the same thing.

Connect both of those wires into terminal two of the above connector diagram.

Connect the green/black wire into terminal one.

Go to the fan plug, and actually figure out what is what. Connect the brown wire to the ground lead of the fan.

Take the low and high speed wires, splice them together, then connect them to the positive lead of the fan.


That's it. Your shit will work. Car gets hot, fan turns on. Push A/C button, fan turns on. Correct amperage fuses stay unblown. Fusebox stays unmodified and most importantly unmelted. Life is good.

[Schwarz325]

i will try that tomorow, thanks alot for the help fellas!

[M3 euro ltw]

Looking in from the outside...

Oh and the temp switch plug is pretty much gone so i don't even know which wires go to which pin on the switch. I may just leave that unplugged.

I'm not an E30 guy, but someone please point him to an ETM.

It is so easy to read those, all the wire colors and pin numbers are printed in black and white, and he can re-wire his fan switch from the radiator, and be done with this.

The part number for a new plug is in realoem.com, and it will take zero effort to rebuild the switch properly.

[Schwarz325]

Alright so i tried that and it worked as long as the wires were straight. I tucked the wires in, and turned it on. When you move the wires coming out of the fan the speeds change, then it stopped and the fuse popped again.


I think i'm just gonna put the stock aux fan in and hope for the best. I mean the stock aux should work the same, once you push the ac button it comes on too.

This is irritating the shit out of me.

[Mossman]

Holy shit man if you get out of this without a car fire it'd be a miracle. Wires don't care if they're curved, clearly you have a shitty connection somewhere that is getting jostled when you move the wires. If you're gonna just jump into electricity without understanding shit do it with a multimeter not a big fan capable of drawing enough current to melt your fusebox. And don't put higher rated fuses in. Honestly if I were you I'd replace all my fuses with 1 value lower because I'm sure there are a few ticking time bomb wiring jobs on your car.

You got plenty of good advice, just tear out everything you've done, replace any melted wires, and start over. Check for power with a test light or multimeter not the god damn fan.