Ohohh well mevtroubleshhot

[Oli77]

It has been very cold in KY. Last night my son called because when he parked the car (E46) in the garage, the electric cooling fan was on. And stayed on for a good bit.
He unplugged the battery. This morning, there is coolant in the cooling system. Lots of mayonnaise in the oil filller spot (car has done this most winters). I know this is not good, means there is emulsified coolant in the oil.

If he plugs the battery, the fan turns on this morning.

Clearly engine is cool, so is a sensor out of wak, or worse, his oil separator failed in the cold and with the short trips he takes?

We have not started the engine.

I will go there tomorrow. What should I look for?

[Oli77]

The title was supposed to say help me troubleshoot. ��

[John in VA]

Bad final stage resistor/fan speed resistor/"porcupine/hedgehog" (FSR) will cause the fan to run even with the car off. It's up between the left edge of the glove box and center console. Plenty of YouTube videos on this.

The black rectangular box (don't recall the name for it) on the top of the fan shroud/housing itself can also go bad.

[Oli77]

Thanks John.
I remember this.
Little hard to get to but likely an easy fix.
Will attempt this and report back.


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[GeorgeH]

FSR shorted out won't cause the engine cooling fan to stay on.

The black box on the fan shroud is the methane sensor for automatic recirculate for the HVAC system.

The electric controller which is part of the fan is likely bad.

[John in VA]

The electric controller which is part of the fan is likely bad.

Thanks for clarifying that, George! I ended up getting the CoolXpert Cooling Fan Assembly from FCP.

[Oli77]

Uh oh. Thanks George.

Was about to pull the trigger on an FSR available locally.

New fan assembly then?

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[GeorgeH]

I've been happy with the ACM fans lately. They are the only ones I can find still made in Germany, everything else seems to be china, taiwan, etc.

I buy ACMs from my local wholesale dealer, I can't find them online unfortunately.

[Oli77]

We located one locally from O'R's autopart (~325$) but they have to order them after all.
Searching for a good YT video on the Fan swap.

[Oli77]

Turns out I have done this job multiple times on the e46.
Should have it sorted tomorrow.
Fingers crossed.