take pictures of the reactions you may be getting from the mold.
I am not sure if the fan will totally eliminate the mold problem but it sure would help.
Get online and copy info on how dangerous mold is.
call the manager and let them know if nothing is done about this, then action will be taken.
easy enough huh?
I have been aggressive with many managers in my rental past, and it shouldnt take much to convince this guy that you feel that he doesn't care about health. And believe me, it doesnt take much to convince em. They don't want to lose their license or whatever they need to keep renting.