i have a 2004 2500 sprinter. recently had a customized electrical system installed with a mega alternator, inverter and 4 marine batteries. since i got it back from the customize shop, i noticed a fan that sounds like it is under the drivers side floor come on after running the van for a while. i did not notice this fan before. it runs for a second after shutting off the van and then stops.

is this normal? was this running before but i never noticed it (which is possible since i've had the van for only a month before the electrical system was installed)?

thanks