Fill a Fiberglass windshield?
I replaced my CJ stock heater with an aftermarket heater and plenum. The pressure out of the front vents is powerful but sucks with the defrost. I think it has to do with the windshield being hollow and wasting pressure around the inside. Testing my idea I took the pivots out and stuffed rags in the corners and tested the defrost, pressure went up great. My question is, is there a reason you need to keep it opened up? Can I fill the corners with silicone to keep the air to the defrost vents?