Not sure if this is the right place to post but I have a 2004 G35x and I have water dripping from under the driver side dash. It looks like it would be under the vent. I have had AC on just about all day. Could it just be the condensation from having it running all day or something else? My floor mat is pretty damp as well.

 

See if you can trace where the waters dripping from. I haven't had that happen on my G but on a different vehicle I'd have water drip on the passengers side and noticed a small hose had came loose, might just be the same problem.

 

It looks like it's just the bottom of the plastic piece where the air comes out that's condensating. I will have to take that cover under the steering wheel off and see if I can see better.