I haven't seen this with the Town & Country specifically, but some car models have a tendency for the condensate that collects on the air conditioning unit, which is supposed to simply drip down onto the road below, to drain into the floorboards instead.
More than likely yes.
water in passenger floorboard, where is the hose that would cause this?
A bad compressor belt can cause a whistling noise while running the air conditioner. A bad engine can also cause this noise.
A damaged heater core will cause coolant or water to leak onto the passenger floorboard.
There are many things that can cause vibrations in a 2000 Toyota Avalon. One such cause could be a bent rim and another cause for the vibrations underneath the floorboard is the engine.
heater core
sounds like you ac compressor is about to crap out.
Water.
It could, the computer will disengage the ac compressor if the engine temp is too high.
If you left the vent open, or if the vent under the windshield is full of leaves, it could cause rainwater to flow into the floorboard.
Compressor not running, blown fuse, low of freon.
While running your air conditioner, the vents should be closed so that warm air from out side do not enter into the room,which may cause damage to the machine in the long run and it will fetch more time to cool the room.