Aux Fan install questions.

[z122643]

So I bought an 90 E30 (manual), last owner (genius that he was) decided that the reason the engine was overheating was a faulty Aux fan and not the leaking water pump.

Our star studded self proclaimed mechanic, decided to rip out the old OE fan and install one from Pepboys with zip-ties. He bypassed the radiator thermostat switch and ran an off/on switch to with-in the cabin.

I am now repairing the vast amount of damage that our (prodigal mechanic) has done by returning the Aux fan to OE with a new radiator thermostat switch. *However I am a little confused, this may have to do with that I do not have an example to follow. There is only one bundle of wires coming from the (OE) Aux fan and it appears to plug directly into the thermostat switch in the side of the radiator.
-First is this correct?
-Second, where is the fan getting it's power from?

Any help is appreciated, Peter

[scottinAZ]

rad switch controls two relays in the fuse box, high speed and low speed. Best thing to do is get ahold of the wiring manual for your car (have to search, dont have a link handy) and make it look factory. Basically, there are three wires that go to the fan, high speed, low speed and ground.

[vpilarrt]

There's a resitor in the harness that reduces the fan voltage for the low speed mode. Elec schematics: http://wedophones.com/Manuals/BMW/19...g%20Manual.pdf

[bmwm42]

Fan doesn't plug into thermo switch connection is on drivers side by the headlights

[z122643]

So the radiator thermo. goes to the relay, and the Aux fan goes to the relay?

Thank You for the electrical diagrams, very helpful!

[vpilarrt]

Yep.
You're wlecome.

There may still be the plug for the fan on your car. As bmwm4s said it is behind the driver's side headlight and is triangular with 3 contacts. If you but a OEM aux fan with its harness intact it will have the resistor and correct plug on it.