Aux Cooling Fan troubleshoot? [Archive]

Jehu

07-28-2010, 08:19 PM

I was greeted the other day by myaproximately One year old Made in Germany Aux Cooling Fan suddenly going at High RPM the moment I turned the Key to Position #2 when about to start the car. The air temp at the time wasn't even 90 F.

I removed the radiator sensor plug to jumper and see what was up. I got High but no low rpm.. when I jumper the Low wire I hear the Relay clicking but the Fan doesn't spin. Is the Resistor failed? I actualy went and bought a brand new relay from BMW but may not have needed it. The wires in the relay box leading to the low speed relay all appear intact but I haven't used a volt meter or ohm meter to check anything . oh and the two fuses are OK. Any ideas?

bimmo_2007

07-29-2010, 06:14 PM

I was greeted the other day by myaproximately One year old Made in Germany Aux Cooling Fan suddenly going at High RPM the moment I turned the Key to Position #2 when about to start the car. The air temp at the time wasn't even 90 F.

I removed the radiator sensor plug to jumper and see what was up. I got High but no low rpm.. when I jumper the Low wire I hear the Relay clicking but the Fan doesn't spin. Is the Resistor failed? I actualy went and bought a brand new relay from BMW but may not have needed it. The wires in the relay box leading to the low speed relay all appear intact but I haven't used a volt meter or ohm meter to check anything . oh and the two fuses are OK. Any ideas?

Yeah, it's possible! Check the Resistor and the low speed supply.

Blitzkrieg Bob

07-29-2010, 07:32 PM

Got a meter?

check to see if the resistor is fried... Had the same thing a while back and it made me crazy for a day trying to figure it out

Jehu

07-29-2010, 11:50 PM

Thanks gents. I can get a meter and may be just source a replacement resistor and splice it in and see anyway.

bmwrp8

08-06-2010, 01:07 PM

Thanks gents. I can get a meter and may be just source a replacement resistor and splice it in and see anyway.

had a similar problem too 2 weeks ago turned out to be the socket of the aux fan was not making contact so i cleaned it. Was brittle too and whenever the fan turns high mode socket becomes abnormally hot so im looking for a replacement socket.