We had some really heavy rain the last few days here and while driving home, I noticed a waterfall coming from behind my glovebox. After some research, I removed the cowl vent grille and looked inside. I saw a pretty good size rust hole just below where the air intake enters the car. I was considering spraying some flex seal stuff on it, but I think the hole is to big. So, since I don't have a/c and my vents don't blow air anyways, can I just put something over the holes that the grille covers and place the grille back on, or does this area serve another purpose besides for the a/c and vents? Or would i be better to tape the rust hole up and then spray the canned sealer over the tape to seal it? Thanks