1996 Plymouth Voyager Leakage after rain

The dash on the passenger side of out van always leaks after it rains and completely soaks the passenger floor board. It comes out behind the glove box and it has now got into the blower as it blows a mist when the AC or heater is on. Are there drainage ports that I need to check by the front windsheild wipers? I do not beleive that it is the heater core as the water only appears after it rains and there is no antifreeze smell nor loss of coolant.