Just a quick question and hopefully someone with experience on this can chime in.

Yesterday was the second time that I noticed this happening. We have a friend whose driveway is a steep uphill, but only 20 yards or so long. We usually get to their place after about 45 minutes of freeway travel.

For a second time now, I have noticed that when I park the car on their driveway, the auxiliary fan (the electrical one in front of the radiator) stays on for a few minutes. It doesn't do it after driving on the freeway in other occasions though.

Yesterday the weather was cool and rainy, no A/C was on... just a normal 80 mph travel for about 40 minutes, and up this steep driveway for about 20 yards.

Both times (yesterday and a couple of months back), I have waited a minute or two for it to turn itself off, it hasn't. I start the engine and stop it again, and it stops.

I am assuming there is not much to worry about here, but it is just interesting to see this repeat itself only in this scenario. Is this the normal behavior? how long does it take for the fan to switch itself off? (yesterday, it was on for about 2 minutes before I turned the car on/off and it shut itself down.)

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Currently driving: 2011 E70 x35i , 2011 E90 335d
Previous BMWs: 2007 E90 328i , 2005 E53 3.0i, 2011 F10 535i (6spd manual)