So every since I bought my '89 sedan, there has always been a water leak from the dash. It only leaks under very intense rain, or when I take a hose / pressure washer and aim directly at the cowel. I did some digging and found out its getting in through the fresh air vent hole in the cowel, and leaking in through the HVAC ducts under the dash (conveniently right above the fuse block).

The little shroud above the hole for the vent is present, and the rubber gasket that is attatched to it is in good shape. I have replaced the plastic clips that hold it down, and it didnt change the leak.

Is there a way to fix this? Or can these cars just not get too wet? I don't want to seal that hole, but I would rather not have a leak than have a fresh air vent.