My passenger side water leak resolved!
 

A while back I posted about an issue with a wet passenger floor that I had believed to be related to a backed up HVAC drain line ---> Wet floor
I continued to find a soaked floor even with minimal use of the AC due to cooler temps I was finding a soaked floor board, it had to be something else beside the AC condensate.
I removed the cowling and sealed up the access port just above the fresh air intake thinking that maybe it was leaking as I was finding the intake plenum full of water also, and it was above any possible condensate points, still I ended up with a wet floor and a seized blower motor due to water intrusion / emersion :(
I had removed the passenger kick panel and left it off as well as the beauty shield for the HVAC area, with the torrential rains we have been having in central Texas it wasn't long before I noticed water droplets running down the interior quarter panel behind the kick panel.
A quick inspection of all seals and all seals were found to be soft supple and sealing.
I removed the side dash access panel and the passenger "A" Pillar moulding and started running water over the windshield and low and behold with the camera running I found the leak!
I had my windshield replaced by Safelite about 2 years ago for a rock crack
I called up Safelite, it is a lifetime warranty so they are having me come in first thing tomorrow morning to address it... hopefully it's a full replacement and not just jamming sealant into the leaking area as I could have done that....
I'll follow up...
I've attached a couple of pictures of the HVAC fresh air intake, which turned out to not be the problem, but thought they may be helpful...
Attached is a youtube video of the leak...

great work. water leaks can be hard to locate.

Thanks! it was a bit of a bear...
As a tech you try not to go into a problem with too much of a preconceived notion but you do have to have a metal work list or reasonable ideas, in this case for me the logic was:
1) HVAC condensate line block- nope not it
2) dried out or broken firewall seals or gasket- nope not it
3) failed body seals or broken / mis-directed sunroof drain lines- nope not it
4) removing many interior panels, shields, carpet and padding and systematically flooding different areas in a controlled manner so as not to mask or misdirect the root cause- dig dig dig!
5) Knowing the vehicle history and remembering that the windshield was replaced ~ 18 months ago- dig dig dig!

It did indeed take time to identify and resolve, so keep that in mind if you have a leak and take it in for repair...I though my first "fix" was it, and it was not even close.

I showed the tech my video and said yeah, they would pull the entire windshield and reseal, he did mention briefly repacking the the seals but he quickly dismissed it as not likely an effective fix for this case.
I did verify that the seal indeed was replaced and I happened to walk by the service bay and saw the windshield pulled. It's not really a seal per se, but a thick bead of flexible sealant, he said the last guy that did it, went with a thin squiggly bead, and should have applied it in a thick straight bead.
He said he saw no obvious voids and did suggest I verify the sunroof drain lines just in case, I assured him I had been down that road :)
I will note that I had noticed a very light high pitched whistling from time to time, I'll have to listen for it to see if that was indeed the leak I was hearing....

Thanks for this post, It is helping with my trouble shooting

in the below picture you posted, there is a white material on the 3 sides deflecting water. My Tahoe doesn't have that, what material you have used here?

https://chevroletforum.com/forum/att...820_172331.jpg

it looks like household door weatherstrip like you would find at the home improvement store.

Blazer leak on floor
 

July 2020 thru the beginning of August 2020 I have had 2 to 3 inches of water on my passenger side floor. I read this forum in those months to get any help, ideas, or a solution to the problem. with the help of a friend we started troubleshooting: Cowl covers, door seal, pins and bushings in the door hinges, weather stripping, kick panel, windshield and more. NOTHING worked! My Blazer was painted in August of 2020 so my friend had an idea with a solution to the leak......On the side of the leak (passenger side) the front of my roof rack did not have the proper screw or rubber piece attaching to the roof. The roof rack was removed when the Blazer was painted but it was not re-installed correctly. My friend put the proper screw and plastic piece on and we waited for another down pour. THE FIX WORKED! I hail my friend as a genius! I would have never thought of the roof rack.

2015 Tahoe passenger side leak
 

make sure the drains are clear too

Leak passenger side 2015 Tahoe
 

thanks. Yes blew the drain out with compressed air earlier ftom engine compartment. Easy to do on this model. Part of the investigation.