Well I have this draining problem. The passengers-side floor is wet. When I put the heater on water is running out of AC/ Heating unit under the dashboard. I checked the AC drain.
In my case there is only a short tube coming out of the firewall which is not draining after the use of the AC. I sealed it as I discribed in threads before. Still having the problem. Now my question is there something missing or is it only this build in tube? What else can I do? compressed air? 1999 Dodge Ram 5.9 Magnum.
Thx Uli

 

Leaking heater core perhaps? Smell the water from the floor and if it smells sweet then I would say heater core. Other than that I am not sure.

 

fish a wire into the drain tube and wiggle it around, see if you can break loose a clog.
the little short drain tube stub is normal.
when you say sealed, you mean around the outside of the tube, right? don't plug it up...

 

I'm having the same problem as well. I took the trim screw out temp. to allow the accumilation of water to drain. I tried the coat hanger method...still doing it. Idk what else to do...it all occurs after the A/C has been used.