ive got an 84 el Camino that's been siting out in the rain for a couple of days. I woke up to a wet passenger floor mat today. Reaching around under the dash I noticed the foam inside the heater vent to be completely soaked. A quick search yielded that this could be a clogged drain in the heater box. Does this seem likely? Also is there any common spots to look out for? Unfortunately I don't have a manual for this car yet or a garage to work on it. So before I tear into this thing in the street any help would be greatly appreciated as this car lives outside. Nothing seems to be leaking on the drivers side. So...