electric cooling fan
 

Is there any difference between the Behr and the OE BMW fan ?? They look the same in the pictures but $150 price diff. Anyone have any experience with this ?

I installed the Behr unit on a 528 and works as designed with no issues. Fit & finish was the same as the OE unit.

OK, thanks, good to hear :)

Put in a Behr after the OE fan died in the 3.0. Around 2 years ago. Ok so far.

Original fan was a Siemens.

Same here. Have about 2.5 years on my Behr fan with no more problems

Thanks for the feedback guys, ordered the Behr fan today was the quicker option as well. While we are the fan topic, does anyone know exactly how it is controlled ? Does the control wire send a request signal to electronics in the fan motor to control speed or does the control wire directly turn on and modulate fan speed ? I don't think it's just a transistor in the fan motor like the wiring diagram shows!

The transistor symbol in the wiring represents some form of signal processing or a driver circuit - it's common in BMW wiring diagrams to represent complex circuits with a transistor symbol.

The aux. fan is controlled by the DME/DDE via pulse width modulation, on the third (smaller) wire. The fan driver in the hub of the fan (in the later versions - it's in a separate box on the fan frame on earlier models) uses the PWM signal to modulate the fixed +VE input voltage and control the fan speed.

The DME sends a pulse width modulated signal to the fan to turn it on and control the speed.

Here's is why the fan is so expensive and why you shouldn't buy the cheapest fan.

http://www.xoutpost.com/934347-post3.html

That's excellent information guys Thanks! I guess I should have put a scope on the third wire and check for a PWM signal. Thanks for that link to pic as well, I was going to have a look inside but I couldn't get mine apart! That's a lot of electronics for what it does but I'm guessing a lot of it is to run the brushless motor.

Here's a video on PWM signal for a radiator fan

https://www.youtube.com/watch?v=winfXPvjtgQ

Eric is one of the better mechanic on youtube, way better than ETCG.