I went through extremely deep puddles on the Hudson Parkway NYC curb lane last week without a care in the world.  However.  Water  appeared on passenger floor that day and following days despite vigorous drying efforts.  I've partially lifted the carpet and collected about a liter total out of the carpet backing several times and each time thought I was done. But with more driving, more water appears.  It's as if there's a reservoir/trap somewhere near floor level that motion shakes up so as to wet the passenger area.  Anybody know what I am looking for?  I have not yet crawled under the car nor totally removed the carpet (enough breaking fasteners already!).

Thanks for any advice.

Oh wow.  

There’s an AC drain tube on the passengers side under the vehicle. 

Sounds like debris got pushed in there and clogged it. It’s probably not trapped water but that hose needs opened up to drain the HVAC.  

Try from underneath or pull carpet and remove it. I’d pull it out rather than attempt from underneath.  Pull the carpet back under the dash to get it out and then leave the carpet exposed to dry.  

if you don’t have a warm low humidity garage to air it out in with a fan I’d be tempted to run a dehumidifier and fan in it if it’s cold and low sunlight in your area. 

Edited October 25, 20205 yr by idosubaru

Had similar problem with 90 Loyale. Used a coat hanger and threaded it up from the bottom gently. Don't know the location on your car. Obviously better to access from top so as to not ram more junk up the tube.