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Auxillary Fan not working

Hi everyone,

The auxillary fan on my X5 3.0i is not working. Air conditioning works while driving but not at lower speeds/stops, and coolant temperature shoots up after its been driven around for a bit or if its hot outside. (Which promptly comes back down after I turn the heater on!)

This is a bit of a nit since the car is so low mileage, I don't really know why the electrical fan shouldn't be working (2005 with 55k miles)

I did some research and I found that there could be a number of things wrong with the fan. I stuck a screwdriver into the housing and the fan blades move just fine with no resistance. The odd thing is, when the fan is unplugged then plugged back in, it spins a few times (weakly) then stops.

The cooling system is entirely refreshed, expansion tank, radiator, thermostat housing, water pump, all done at 54k miles

If any of you have any idea or have had a similar problem, I'd appreciate any sort of help!

many thanks

I am assuming you do not have any software that would be able to read the codes. The fan can die and still spin freely. I would find some software to read the codes or pay a shop to diagnose it. A new OEM fan (Behr) is less than $400.

Check this threading for E39. I think E53 and E39 have almost the same set-up.
aux. fan not working - Bimmerfest - BMW Forums

Quote:

Originally Posted by Joshdub (Post 1045821)

I have the peake diagnostic tool, but it doesn't seem to be throwing any codes :dunno: Do you happen to know if it should throw codes if the fan is bad?

edit: looks like if the fan is bad, it will throw codes to the engine control module. I'm going to see if I can find any codes from there

Quote:

Originally Posted by trader4 (Post 1045839)

With the PC based INPA software it will show up, but it doesn't show
up on the typical basic engine code reader, AFAIK. It's most likely you have a
bad fan. It's a very common failure, they are a piece of crap. I've had
3 fail. BMW chose to put a complex variable speed fan with electronics
in it in one of the worst environments. You can even see the electronics
board, it's exposed. It's also supposed to come on briefly as a test
when the car is first started., you could check for that.

Interesting that with yours the engine temp goes up. I got tired of spending $450 for fans, so I've been driving mine with the fan
not working for
two years now. The only symptom here is loss of AC when completely
stopped. Even moving slowly, it works. And the engine never goes over
normal temp. I was on a 250 mile trip last week, 95F outside
and the needle never went past straight up, even when going from
70 mph to stopped at a light.

Another interesting thing is that your failure is similar to mine, in that
the AC continues to work. Others have reported that the AC won't
come on at all. And the controller must see something coming back
from the bad fan, because on mine if I disconnect the fan cable, then the
AC won't come on at all.

Thanks for the response! The coolant temperatures on mine only seem to rise when I am in stop and go traffic, or if I am doing a lot of in-city driving (frequent stops and acceleration) after doing some research on some other threads, the most plausible explanation for rising coolant temps is that the auxiliary fan comes on during times of high engine temps in order to push more air through the radiator in order to lower coolant temperature. So when the fan isn't working, sufficient air isn't moving through the radiator when the truck is at a stop or slow moving traffic, so the coolant temperatures then start to rise. Which makes sense, since once I start moving again, the temperarature drops back down to normal.... What doesn't make sense, though, is the number of people I see who are running without the auxiliary fan and aren't overheating!

There are two fans in a 3.0 X5, the electrical aux fan and a mechanical fan. Could be that the viscous coupling on your mechanical fan is also bad.

update: I installed a brand new fan, and it still does not work. any ideas on what may be wrong??

Edit again! turns out the lower radiator hose sensor was bad... AND the fan! just in case anyone else had the same issues and didn't know what the problem was!

i would have thought when you first start the car, the fan does a self test and spins?. even if the temp sensor was bad would this cause the fan not to spin?.