When i checked the truck this morning. It had not rained much, but maybe 1" over previous 24 hours. I had previously removed the mat from underneath the panel that is directly under the glove box to let it dry. With the mat missing, water pooled in that panel and dripped onto my rubber floormat. There was probably 2 tablespoons of water on my floor mat, and maybe another 2-3 in the panel. My carpet didn't seem too damp, but I did not pull it up to check the mat underneath.
Alright, hopefully this fixes my problem. I ran water full blast from my hose for about 90 seconds and had no leak.
Here is the underside of the cowl, I measured from the wiper arm opening and guestimated which part of the cowl was over the HVAC intake. The white lines on the cowl are those. It does appear that the notch in the cowl is our problem child. I suspect that the weather seal is supposed to keep any water from getting past the cowl, but then as added protection in case it does, there is the lip that the notch is cut out of to direct water around the HVAC intake. But the notch is there to fit the cowl around a support beam for the windshield frame. I think water gets through the weather seal and dips through the notch. There really is no where else for it to go. So the channel probably catches 95% of the water that gets past the weatherseal, but can't do anything about the water coming through where the notch is.
So technically you could probably just put weatherseal above this notch and you'd be fine. But I went more heavy-handed than that.
I found this at Lowes
It has very similar texture to what was installed on the cowl. This is the 1"x1" version. They have a .5"x.5" version. The most "factory" fix for this would probably be to get the smaller seal and replace the seal on the cowl. Here is comparison of the two weatherseals. Also, in this picture you can see that the weather seal is clearly damp, and that there is water on the plastic below the seal. By this time i had handled the cowl a bit and everything was still a little wet from the rain, so possibly that water didn't get there until after I removed the cowl.
Here is where I installed the weatherseal. You really only want about 3/4". I trimmed mine after installing, might be easier to do before installing. I put the weatherseal along the entire HVAC intake. I have no fear of this stuff falling off. Also, you really only get one shot at installing. I was being gentle but didn't quite get it where I wanted and tried to pull it off. It definitely makes a mess and left some residue from the weatherseal. So get it where you want it before you press it. There will be a lot of scraping in your future if you need to move it. I also put a little over the notch on the plastic cowl the way
@peez206 installed his. I tried using the gray foam he had (or something similar) and I didn't feel like it adhered very well. So I used the black stuff, it isn't going anywhere. Once I reinstalled the cowl it fits much more snug to the windshield on the side where the weatherseal is. That definitely gives me hope. On the drivers side there is still quite a bit of play. If I was doing it again, I might put a few inches of weatherseal on that side just to firm up that connection, even though I doubt it would add any protection.