Toyota Repair: 04 Highlander Water Leak, drain tubes, toyota factory

Question
My 04 Highlander, V6 AWD, has 41000 km on. There is a leak somewhere that wet the front passenger side carpet. I have it checked by a Toyota dealer (3 days) but they couldn't find any leak after 5 hr of water testing. They said they checked the air conditioner & found no leak. The leak should be there at least a few months cos' when the carpet (& the chair) was removed we can see the mould. The insulation was wet too. The paper towel soaked clear water. I don't think the dealer did the test while the car is in motion. Any suggestion/comment? It's really bothering me though the dealer will request Toyota to change the carpet; but I really want to find out the problem & have it fix. Thanks a lot!

Answer
The most common causes for water to leak into the passenger side is that the water drain hose from the A/C evaporator is disconnected from the duct and is draining inside the vehicle instead of outside onto the ground.
The other cause only applies if the vehicle has a sunroof.
In that case one of the sunroof water drain tubes is not connected and when it rains or the car is washed the water will leak into the car instead of the outside on to the ground.
Since this problem is still covered under the toyota factory warranty the dealer is obligated to find where the water is leaking in and take all necessary steps to repair this. Replacing the carpet is sensless until the leak is fixed.