Fan Blow after Turning off car on 1998 Mercedes-Benz SL500

I have a 1998 SL 500 and after turning off the car a fan continues to blow air out the front window vents. Any ideas?

Asked by for the 1998 Mercedes-Benz SL500
This is normal on some vehicles if you have been running the A/C system. The idea is to help clear out the moisture in the evaporator housing to prevent musty odors. I don't know if they do that on this model though. How long does it blow and does it turn off by itself?
you might be right because it only seems to do it when its really hot or humid out and air condition has been on. It did run several hours one night was afraid it would kill the battery - thanks for response