The fan runs whenever the engine is warm. It does sem to be a bit random sometimes but it should turn off after a few min. I wouldn't be worried until it stayed on for more than 10-15 min. Mine freaked me out the first time it happened but after I have gotten use to it I don't give it a second thought. Actually nice to think that my BMW is taking care of it self even when the engine is off.

__________________
'03 X5 3.0 -Stahlgrau-