RV Repair: Duo Therm A/C leaking inside unit, roof seal, duo therm

Question
Larry,
 I have a '99 Tropical motorhome. My rear a/c is leaking or condisating back inside my unit. I have changed the roof seal and there is nothing restricting the run off. This leads me to believe that it is condisation. The inside cover collects the water and my ceiling is getting wet. Please help if you can. I am not having any problems with my front unit.

Thanks,
Cary W.

Answer
Hello Cary,

It sounds like you have already done the more obvious things, I believe next I would be looking inside the unit up on the roof. Check to be sure the condensation is draining out the normal drain, if that checks out ok, next look at the drain pan, located under the evaporator cooling coil. Look closely to find out if there is a crack or rusted out area in the drain pan, which would allow the water to seep back into the inside air distribution panel, as it is now doing. Hope this helps you out. Please let me know how you make out with this project.
Regards, Larry