I'm reluctant to help because it's one problem I HAVEN'T had... But let me look.
I do not think it's in the doghouse, and I'm pretty sure it isn't inside the cabin. I've done a lot of tinkering on ours and I'll try to get a look that might help you.
What I CAN say, is that ours drips the condensate way out in front, ahead of the passenger side tire, right at the bumper. So I think it drains right out of the bottom of the Firewall Side of the HVAC cabinet and runs down.
When I can't get at a drain, I sometimes rig a smaller hose to the shop vac and work from where the Resistor Pack (provides A/C fan speeds) or the Blower Motor itself comes off. And sometimes, I use a water hose directed into one of those access points.
If you want to investigate the Resistor Pack idea, here's a pic. The coils are IN the HVAC ducting, and the Connector goes on the rectangular part you can see, held down with two small screws. It'll be on the ducting because the air flow cools those coils.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB