Tonight, I found my front passengers' and drivers' under-carpet insulation was completely wet, front to back, left to right - no outward signs.
It was the A/C drains as in Architex_mA8tey's post #27.
When unplugging them water rushed into an IKEA bag I thankfully held underneath.
I blew them out with an old CO2 fire extinguisher linked to some 1/2" clear hose. I will flush with hot water and ammonia tomorrow and make sure I can see it coming out underneath the car.
I found this when removing the rear footwell heaters which were wet.
Now have a fan heater blowing into the hole where the footwell heaters were mounted.
Will see how well it has dried overnight in the morning and do the other side.
Here is the water, it is full of mould.
Attachment 22361
Attachment 22362