Official Electric Fan wiring thread!

[Josh1254]

Alright guys, I read through everything and can't figure out my problem.

Its a 91 318is with a 95 318ti electric fan and 80-88c temp switch. I have all the oem wiring. The high speed fan kicks on when the temp switch is at 88c. I used a temp gun to check. The low speed does NOT turn on when the switch is at 80c. I tried two different switches too. Also, the low speed fan does turn on when I hit the AC button inside. When I unplug the wiring at the temp switch I can jump the high and low speed and both work great.

My only thinking is the low side of both temp switches I tried are bad?

Any other ideas?

[328ijunkie]

Ninja Edit...
Its rare but possible both low speed circuts are bad or theres the other possibility of you having the wiring flipped for low/high speed as the plugs like to turn to dust over time and youre seeing low speed fire but never seeing high speed fire....

[indecline]

Sub'd for reference.

[Josh1254]

Ninja Edit...
Its rare but possible both low speed circuts are bad or theres the other possibility of you having the wiring flipped for low/high speed as the plugs like to turn to dust over time and youre seeing low speed fire but never seeing high speed fire....

Well, when the temp switch hits 88c the high speed fan turns on. When I hit the AC button inside the low speed fan turns on. So the wiring has to be correct.

If the low resistor is bad, it wouldn't work at all right? But mine does with the ac button and jumping the wires at the temp sensor plug.

Maybe both temp sensors I have are bad?

[f4tj0n]

Was thinking about just using this..

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

Any reviews?

[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.

[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.

[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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[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]

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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[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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[_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

[_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.

[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_]

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.