Official Electric Fan wiring thread!

[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_]

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


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[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!

[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

[328ijunkie]

Have you tried bridging the two pins at teh switch and seeing if the fan fires?

[18rabbit]

Have you tried bridging the two pins at teh switch and seeing if the fan fires?

Yes, and when I do this, the fan fires. So this pretty much means bad fan switch yeah?

[18rabbit]

Yes, and when I do this, the fan fires. So this pretty much means bad fan switch yeah?

Ok, so I bought a new fan switch and same thing happens. I think the fan switch and the coolant temp sensor are getting vastly different temp readings. The coolant temp sensor is hot while the radiator (and bottom hose) is cooler. Coolant gauge reads 3/4 hot. What does this point to?

[328ijunkie]

No one believes me the fan switch is almost never problem ;)

Water pump/thermostat work?

[gotane30]

No one believes me the fan switch is almost never problem ;)

Water pump/thermostat work?

I believe you Dave. :hitler:

[18rabbit]

No one believes me the fan switch is almost never problem ;)

Water pump/thermostat work?

Now I'm a believer!... Yes water pump and thermostat are brand new. Today I pulled the thermostat and radiator. Flushed the radiator with the hose and got a bunch of brown stuff out of there. I drilled a <1/8" hole in the thermostat too and replaced it with hole at 12 Oclock. Then I proceeded to bleed the cooling system using the following protocol:

Jack front of car up
Turn car to 'on' position and run heater full power, fan full speed
Opened bleed screw and radiator cap
Fill coolant using top thermostat hose slowly
Once hose was full, I mounted hose then filled radiator until air bubbles stopped coming from bleed hole
Closed bleeder and radiator

Still overheating. Hoses are rock hard, top hose is hot, bottom hose is cold. Fan still not coming on... Any help is appreciated.

[328ijunkie]

what radiator/overflow setup?

overheat at idle or driving? Have a accurate way to monitor temps?

[18rabbit]

what radiator/overflow setup?

overheat at idle or driving? Have a accurate way to monitor temps?

I realize we are getting out of 'fan switch' territory but I have a m42 radiator.

Today I parked car on hill where front end was at least 2' above level. With bleed screw open I used different techniques ie. blowing in rad fill hole and squeezing lower rad hose and managed to get a lot of air out of the system. Still crept over halfway once I took it for a spin but I felt like I made progress. I will try more tomorrow.

[nau]

Which puller fan should I buy for M52B28 with late M20 radiator? SPAL have 3 different series, which one will fit? Will High Performance fit?
Any advice on AC pusher fan please?

[328ijunkie]

M42 radiator setups are by far the most evil/annoying to bleed properly. The coolant jackets in the engine are higher than the radiator cap usually so the air doesnt want to flow up there....

[18rabbit]

M42 radiator setups are by far the most evil/annoying to bleed properly. The coolant jackets in the engine are higher than the radiator cap usually so the air doesnt want to flow up there....

Ok so I finally got the car bled completely and with a functioning fan! Thanks for everyone's help. I bled it about 5 times over the course of a week and I can say a few things made obvious differences:

Parking car on hill where radiator top was higher than engine.
Filling upper thermostat hose directly first then transitioning to radiator fill hole, and squeezing lower thermostat hose sporadically.
Once radiator is full then removing top radiator support and rotating radiator so that the fill hole is higher than the other side.

I also drilled my thermostats to include a breather hole. I also replaced thermostats too. I replaced it with the shorter one on the right.