If you try to check and see if your evaporator is draining properly you might find the problem. Turn A/C on max and let it run for at least 5 min. Then look under the vehicle. if there is water dripping onto the floor then your evaporator is draining properly. If not. then its plugged, this would result in water backing up into vents particularly the rear because they are the lowest. Try to free up the drain maybe with a wire hanger or something. be careful not to poke too hard and damage the evaorator. that will cost you alot of time & money to fix.