Massive amounts of water pour from under the dash?

This is due to your A/C evaporator drain is clogged. If you look on the firewall under the A/C lines that go into the passenger compartment, you will see a small rubber line coming out that should have water coming out of it when the A/C is on. If you have water on the passenger floor then that is because this line is clogged and that water is backing up, filling the housing and then eventually coming out the blower motor opening.

Take a look at the picture below. This shows the location of the drain and you will want to take a flexible pipe cleaner or something that you can fit into that tube. I would not use anything metal as that can damage it.

Please let us know what you find with this and if you are successful with doing this.

Thanks