Just yesterday I experienced this for the third time in owning the car: I start the car after being shut off for maybe 1-2 hours (engine is still a little warm) and after a few minutes of driving I notice a noise coming from the engine, get out and find the radiator cooling fans are blowing full blast (first time it happened I drove for about 10 minutes and the fans never shut off). I restart the car and everything is fine after. All three times this has happened in the fall/winter, with outside temps in the 30's-40's, with the engine warming up.

I'm thinking it's some sort of software bug and that's why I haven't talked to my SA about it yet. Or maybe my car has a ghost?
Curious if anyone else has experienced this strange behaviour? Car has 40,000 miles on it.

 

Sounds like your fan clutch may be going out on you. When the fan clutch on E39 went out, it was engaged all the time. Replaced it myself, bit of a pain but doable. They make tools to make it easier. I bought one afterward and have never used it.

 

Come to think of it, I don't even know if the E60 has a fan clutch. May have wasted a post.

 

On my other car this is normal (even when the car isn't fully warmed up yet) if the A/C is turned on.

 

Hm, maybe it is normal, but it doesn't happen all the time. I also don't think the E60 has a fan clutch, otherwise that would have been my guess as well.