Auxiliary Fan Question

[fisher99]

I have a 2011 535i xDrive that I purchased a few months ago. Recently the electric auxiliary fan has started randomly coming on, running for anywhere from a few seconds to a few minutes, and then shutting off. Doing this over and over again. It will even do it right after you start the car and before the car has had a chance to warm up (40 degree temps outside). I assume that there is a switch somewhere that is supposed to kick this on when engine temps get higher than the standard engine driven fan can handle? Maybe my switch is flakey all of a sudden? Anybody know where this is located and is this an easy DIY job?

Also, is it normal for the electric fan to be really loud? It sounds like a small jet engine when you are standing anywhere near the car. It's not a squealing noise, so I'm not suspecting that there are bad bearings/bushings or anything. It's just an extremely and annoyingly loud fan. Is that normal for these cars?

Thanks

[White94RX]

Have your codes read out. It's possible that your water pump is on the way out and its kicking the fan on.

[fisher99]

Thanks for the suggestion. I just hooked up the code reader and there are no codes. No "check engine" light either. Do you know if this is a variable speed fan? It seems to rev up and then rev back down. Usually doesn't stay on for more than 30-60 seconds and then revs back down, but will rev back up again in 30-60 seconds. Sometimes will stay off for a few minutes and then start cycling on/off again. It usually does it more frequently when the engine is cold, but will do it when warm also. It will start cycling shortly after you start the car, with ambient temps in the 40's, so I know it isn't actually heat related.

[Stück]

The fan is infinitely variable in speed, it is pulse width modulated by the DME. As said above the most common cause of the fan running at an inappropriately high speed is a failing electric water pump.

A generic code reader will not give you a complete and total view of what faults are stored.

[fisher99]

I'm using the "Torque" app on my phone with a bluetooth ODBII reader. Are you saying that the 535 generates codes that a non-BMW code reader can't see? I can understand that a generic code reader might not give an accurate BMW specific description of a code, but I would think that it would still show any codes that have been stored. Mine is not showing any codes. Nor is there a "check engine" light on the dash.

Thanks for the verification that this is a variable speed fan. It gives me some hope that when it needs to run that it won't necessarily run at full speed where it sounds like an airplane waiting to take off...

[fisher99]

Well, in case anybody was wondering, it was the water pump, as I found out the hard way. You can see my other post under "Did I Get Robbed?" if you want the details.

[White94RX]

LOL. Sorry for your troubles! I just might know what I'm talking about..... I've been around BMW's for awhile.