It's possible that the HVAC box itself has a leak. It is plastic, IIRC. But, checking the evaporator drain plug would be good. I think mine is plugged up pretty good as well, but no leaks as far as I can tell, but I don't see ANY water come out after running the A/C a while.

 

Today I had the AC on while running around for hours and towards the end the water started pouring out. Where would I check for the plastic to be broke? And where does the evaporator drain start? Like where is all of this stuff? All behind the glove box?

 

I'd take a short piece of wire and try to clear out the drain tube from the firewall side, or give it a couple blasts of compressed air. Might just be some crap in there partially obstructing the drain.
If that doesn't stop the leaking, the housing might be loose or cracked. Not fun to get at, it's the same process as getting at the heater core. Might see if you can pinpoint the leak and RTV it from the outside.

 

Is it the big round hole in the firewall behind the washer fluid reservoir? I stuck a piece of weed wacker string up it and it seemed to stop at the firewall. Should it go further or does the drain hose only start there?