1999 Dodge Ram Water leakage

I have a water leakage onto the passenger side floorboard. The leakage is water only, no antifreeze. It seems to be condersation from the A/C, there is water on the bottom of the blower housing behind the glovebox above the floor. On the firewall near the housing assembly is a pipe, assume to be a drain designed to remove the condersation. Blowing compressed air into the pipe removed some water and trash. The leakage ceased for a few days but started again. I assume condersation is being blocked by possibly mildew into the housing. Is this the problem and if so, how can this be remendied?
Thanks for your efforts,