Strange wet spot in carpet

[ukrkoz]

07 Tahoe LT

I have strange wet spot on the driver side, in the carpet and padding, right where my right heel rests driving.
Spot is about 4-5 inch diameter, pretty circular.
NOTHING to the sides of it is wet. Carpet on the driveshaft well, firewall side, all is dry.
OEM floor mat has no holes in it, to assume, that water drips off my shoe and through it.
I had windshield replaced in March. Installer, bless his heart, replaced it again a week ago.
I had carpet dried out like desert, with portable heat fan.
Spot is back.
There is no floor plugs, best I can tell, there.
Any ideas? Drain plugs for AC are nowhere close. Is there heater core drain that could cause that? Truck does slowly take coolant. Slowly. I add maybe a cup in 2 000 miles. Engine had heads done. I added UV dye to coolant few months ago and could not find ANY leaks anywhere.
What trips me is that everything around that wet spot is bone dry.

 

[Joseph Garcia]

Did you check immediately above the wet spot under the dash and see if something is wet above and is dripping directly downward onto that wet spot?

 

[ukrkoz]

Just did. UV light included. Nothing. All dry. NO signs of any water or similar. And, far I know, there is no water lines above the gas pedal in the dash. Heater core is off to the right of the driveshaft well. Spot is centered about 4 inches towards the rear off the gas pedal lower edge.
1st windshield replacement was done by one of the techs that work for the guy, who did about 5 of our windshields by now. Superb job every time. He warranted it and replaced it himself. And that AFTER he was here 2 weeks ago, stripped everything around windshield and checked everything, headliner included. Nothing. Man spent a good 1.5 hour looking for any signs of leaks. He even sealed those clips for molding in pillar A, as he saw them leak water inside on some cars.
I safely bet, windshield is not the case. Unless there is crack somewhere weird. But truck was not in any accidents. Just age and miles.

 

[ukrkoz]

Any chances, moonroof can do this? But, then again, headliner is dry and clean. And, anything to the sides and up from the spot is dry. It's like as if it's leaking from the bottom UP. Floor plugs normally do this but there are none there.

 

[Bill 1960]

Just leave a balled up towel above the wet spot to confirm it comes from above. Then you can relocate a dry paper towel or tissue to chase it upward to the source.

Or it will tell you it coming up from below.

Liquid leaks do many odd things and can travel horizontally on seams, cables, all sorts of channels.

 

[5StarG3neral]

Following this because I have the exact same issue with my '13 Yuk

 

[ukrkoz]

Just leave a balled up towel above the wet spot to confirm it comes from above. Then you can relocate a dry paper towel or tissue to chase it upward to the source.

Or it will tell you it coming up from below.

Liquid leaks do many odd things and can travel horizontally on seams, cables, all sorts of channels.

Balled towel? But I do like paper towel sheet idea. Of course, no rain today but it is supposed to rain next few days. Indeed, if I spread paper sheet on the floor, it should show if it drips down from above. I'll also stick some onto firewall and under the carpet, towards the driveshaft well.
Thank you

 

[Rocket Man]

Water can also run down from the firewall and pool in a horizontal area without leaving a trace on the firewall or the jute.

 

[avalonandl]

Possib;e windshield leak?

 

[Rocket Man]

Possib;e windshield leak?

Read post #3.