Official Electric Fan wiring thread!

[marek|steezkal]

Interesting, my wiring for high or low is the same gauge.


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I believe the 2 circuits have different size fuses in the fuse box

[18rabbit]

Ok guys, so I bought a project e30 m50. Wiring was kinda cut up. I have a pusher fan on a m42 radiator. Power to fan (blue) goes to blue/black and ground from fan (black) goes to brown. On the fan switch side, when gray and yellow touch, the fan works (I soldered these to factory wires). But when plugged into fan switch, even when coolant temp needle is at 3/4 (over halfway) the fan still isn't kicking on. Does this mean fan switch is bad? I just bought it... It is a 82* fan switch with a 80* thermostat.

Let me know what you think!

[_Keith_]

Interesting, my wiring for high or low is the same gauge.


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[328ijunkie]

You can use either 2-3 pole fan switch with an aftermarket fan, you just have to keep in mind that aftermarket fan setups dont have a resistor in place so the 'low' speed isnt going to be really low speed, in addition you shouldnt run an aftermarket fan on full speed on the low circuit because the wiring isnt designed to handle that much load..

[_Keith_]

So I have the car wired for obd1. That does not change the factory ac fan wiring. Mines a early model 87 325is.

What I did was take the plug behind the driver headlight trace them to the ac fan switch. Cut the lines red goes to power on fan and the brown/ black is ground. I capped the black for now as I may switch it to have my fan come on sooner. I am running a three prong.

[mcdougal]

Ok so I figured it out. I'll post some pictures to help those deleting all fans and running one electric fan with a 3 pole thermo switch.

You were able to do it with the 3 pole switch not the 2 pole which is commonly used? Heck I'm still trying to figure out the 2 pole.


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[_Keith_]

Ok so I figured it out. I'll post some pictures to help those deleting all fans and running one electric fan with a 3 pole thermo switch.

[_Keith_]

Wow a lot of info, trying to decider it all is a lot.

I have a pusher 16" spal. Ac removed and aux fan. I have a 3 poll switch. So can I hook up the high side wire to the low side on the temp switch so that the fan comes on with the lower temp and be running as a high speed?

Car is a 87 325is with a s52 obd1 setup

[mcdougal]

I found this diagram on wedophones which shows the wiring for the high and low temp switches I have - 2 GN/BK wires into one pole and 1 BK wire into the other pole of the stock high temp switch.

The way I understand it is that I want the fan to run at high speed when switched on by the new temp switch. In order to do this, wouldn't I just remove the connectors from the stock high temp fan switch and plug them into the new switch?




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[mcdougal]

The large gauge wires for the fan power come from the fusebox relays, the fan switch (small gauge wires) fire that relay. The fan switches are what youre calling 'temp plugs' you need (at least one of) those. Thats what fires the fan relay which then turns the fan on...

The fan connector is plugged in to the stock location which means it has power, right? Assuming the answer is yes, this means I just need worry about figuring out how to fire the fan relay. This will involve connecting the two prongs of the single fan switch to some combination of the wires that are coming off the two fan switches pictured above?


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[328ijunkie]

The large gauge wires for the fan power come from the fusebox relays, the fan switch (small gauge wires) fire that relay. The fan switches are what youre calling 'temp plugs' you need (at least one of) those. Thats what fires the fan relay which then turns the fan on...

[mcdougal]

I've read this entire thread and I'm still confused. For reference, I'm trying to get my stock auxillary fan to work as a pusher fan. A/C has been deleted.

In the first post it looks like Dave shows the green/black blue/black and brown wires that are located before the plug spliced directly into the 2-prong temp switch. If this is the case it would mean that the other side of the plug, which contains red brown and black wires and connects to the fan, is disconnected. Obviously the fan side of the connection has to be connected so I have to be misunderstanding something. Should I keep the plug connected as-is and just splice the temp switch into the green/black and black/blue wires?

Here is a pic for reference.



Do I do anything with the wiring for the stock e30 temp plugs or can it be deleted?




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[Klug]

Just wanted to chime in here since for some reason there is A LOT of confusion and hope I can help someone out in the future.

I just swapped out my OEM radiator for a Z3M radiator, its a little bigger but still enough room to run the clutch fan. Anyway, being that I never wanted to rip out the radiator again and I do not have an Aux fan anymore (Removed my A/C) I got a SPAL 16'' Puller. Here is what I did to make this work, its easy and simple (late model 325i with M20)

1) Mounted the 16'' Puller to the right since the water pump (where the clutch fan was) will hit the electric fan.
2) My Spal fan had two wires, +12 and ground. Wired a 30 AMP inline fuse to the red (Be safe people!), then connected it to the Aux fan wiring (Black/Blue for HIGH) and the black ground wire to the Brown ground. I sealed this up with electrical tape after the pic was taken, don't want any moisture to get in there.
3) Put in a 82*C switch to the radiator and wired it with the BLACK/BROWN and BLACK/GREEN

Now the fan will kick on HIGH when the thermo switch hits 82C (I have not gotten that hot yet, but jumped it and verified it works)

This works for me being that the Z3M radiator is a 3-pass and I've read reviews of M20 guys not needing to run any fan due to the increase in cooling. Good luck.

[Tchao]

$50?! For a relay and temp switch? No thanks.

Just use BMW's temp switch and grab a pigtail from a junk yard for free. 40amp relays with harness are under $10.

[f4tj0n]

Was thinking about just using this..

http://www.catuned.com/relay-wire-kit-w-probe

Any reviews?