My passenger discovered water on the floorboard during a long drive in my 2001 Grand Prix GTP. I had the A/C blasting on "Max" since it was a really hot day in South Florida.
I got the car home, sucked up most of the water with a wet/dry shop vac and pulled back the carpet to let it dry.
Then I went and did some online research. Apparently it's a common problem for the rubber elbow cap on the HVAC system's condensate drain pipe to become clogged with debris or mold. The water backs up and starts leaking from under the glove box area.
I took pictures of the process to remove, unclog, and snip open the rubber elbow to fix the problem and prevent it from happening again.
Here's my guide -
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I hope someone finds it to be useful to keep their passengers' feet dry. :)
Cheers, Paul Michaels Ft. Lauderdale, FL