Water under dash of car

I have a 2008 Dodge Avenger and my son drove it a few weeks ago to NYC which is a 6 hour drive one way and returned the same day. During the trip he said there was heavy rain downpours almost the whole time. When he returned home he at first noticed the passenger side floor was saturated with water and then he noticed the driver side was also wet. Since that time, when you turn a corner you can hear water moving from one side of the car to the other, depending upon which way the car is turning at the time, but usually to the left. We cleaned out the vent holes underneath the cowl, which seemed to be plugged. I thought it was fixed, the drain holes are unplugged and it is still doing it. Where else can it be coming from if it is not overflowing the vents? Someone mentioned that the air conditioning drain line may be plugged. I ran a hose over the top and it does not leak, it seems like it only does it while driving in the rain. If you can give me any advice it would be appreciated.

It could be the air venting system collecting water and dripping it under the dash. That’s supposed to be prevented by Dodge’s clever routing of the air vents, so any water that accumlates gets drips outside the car, not inside. But that part might be clogged up. If he used the AC during the trip, I expect this is the AC drain hole plugged up. Since you can still hear the water moving around when you turn, that’s my guess, the AC drain hasn’t been unplugged correctly yet.

Do you have a sun roof?

No, there is no sun roof.