I had a recent problem with water dripping down in the passenger foot well. The water was dripping from the black box in the center area. The carpet and mat was wet and on the mornings, the damp smell was evident.
I felt the water whilst it was dripping and it got colder the longer the air con was on.
It was the condensation from the air con!
Usually, this condensation drips through a drainage pipe and lands on the floor, under the car.
I have learnt that sometimes, this pipe can be blocked up with dirt or whatever. If the pipe is blocked, the condensation can not escape via its normal route and therefore, overflows by the black box in the center area of the car (under the stereo area)
Solution – Jack up the car at the driving side – Secure the car accordingly.
If you get under your car, you will see a small drainage pipe coming out of your car. It will be close to the center area, near to where you would expect the pedals to be. Use a thin pen or pencil and push that up a few times into the drain pipe. You can also use any thin plastic item too to try and clean out the pipe.
This worked for me. Now with the Air Con on, I can see the water leaking through the pipe and not inside the car. A lot of crap came out of the pipe too, which proved that it was clogged up.
Hope this helps.