E39 - Fan Active Even After Car Is Switched Off

I recently bought a 2nd hand BMW 525 TDS Touring (E39) and everyday I discover some new features in this nice car.

This morning I noticed that, if I go keeping the air conditioning active, when I stop the car and switch it off, the small ventilation fan keeps working for long time.

To better understand the problem, I made a test stopping and closing the car with myself inside and I could notice that the small fan keeps working for at least 10 min.

Now I have not clear if this is a defect (which I should fix soon to not loose the battery charge) or it's a normal behaviour (maybe there is timer longer than 10 min).

Any idea on this ?

Thanks. Alberto

-----

The e39 has a neat option that allows the HVAC to run even after engine shutoff. This allows operation while at a prolonged stop (train, bridge up, etc.). I believe it can be turned off, but let me look into it further. The e39 owners handbook has info on it.

Bill in Omaha