Evaporator Drain Tube Help

I have a 97 Explorer and the little tube that protrudes from the firewall does not drip. The condensation is dripping from the actual box that encases the evaporator core. I am getting this musty odor and suspect this is the problem. I pushed a screwdriver about 4 inces up the pipe and never hit anything, still not draining. How far does this pipe go and does it bend upwards, does anyone have any experience with cleaning this tube. Please Help!!