Everyone has that problem, it is the 3 drains for the wiper cowl.
If these drains are clogged ( and they usually are if the car is ever left outside ),
then water backs up until it can overflow into the fan inlet, thus causing what you describe.
The solution is to remove the cowl cover ( must remove wiper arms first ), then clean out the drain tubes.
BE CAREFUL NOT TO KNOCK THE TUBES LOOSE !!!!
Some used air, some used water pressure and some a coat hanger.
Good Luck !!!!!!