I recently found an accumulation of water under the floor rug on the passengers side of my 2003 Dodge Dakota truck. I have no idea from where it is coming.
Most likely it’s coming from the AC evaporator. The drain tube that’s supposed to allow condensation to drip onto the road is clogged, and the water is dripping out the heat vents instead.
Clear the drain tube and the water will go where it’s supposed to go - outside.
Then you’ll have to lift the carpet and remove the padding underneath in order to dry it. The padding will hold water for a LONG time if it’s not dried correctly, and a shop vac won’t remove the water from under the carpet.
I can think of a few things. One, it could be that the drains from your ambient air intake are clogged up with debrish. Two, it could be that the window on the passenger side has failing rubber seals, and the drain holes in the bottom of the door are clogged thus allowing a build up of water in the door that is leaking onto the floor. three, if there is a rust hole in the floor, it could be shipping road water durring storms. four, and this is an outside possiblity, it could be condensation from the AC duct. five, do you have a small dog that rides on the passenger side?
There was a crack in the seam between the inner fender and the firewall on my 2000 Blazer. The water was running down the seam under the carpet and padding. It accumulated on the floor and worked its way up through the carpet.
Use a hose to pour water into the windshield cowling. Use a flashlight to inspect under the dash, the light will reflect off any water coming in the truck. That’s how I found the leak on the Blazer.
You Can Check And Do All Of Things Suggested So Far, But . . .
The bad news:
. . . Chrysler says that many 2001 - 2004 Dakotas have a particular problem that causes a “Passenger Compartment Water Leak”. The water gets in between the HVAC housing and the bulkhead (It’s what I call the firewall). Water can run along the drain tube (the one that sometimes clogs) and can back-up into the cabin because a foam seal (between HVAC housing and bulkhead) fails. According to Chrysler the result is wet passenger compartment carpeting.
The good news:
This is a piece of cake. Locate the A-C evaporator drain tube opening in the firewall behind the engine, under the hood. Repair is made using RTV sealer (available everywhere) around the perimeter of the tube opening to seal the joint between the firewall and the seal (HVAC gasket) and also around the drain tube where it contacts the seal.
If it has a sunroof, I would start by looking for a blocked drain, there are four of them.