Drain is plugged on Dometic AC How do i unstop?

either a stopped up drain or bad pan. try to unstop drain. units usually hav a auxillary pan under unit that drains to a area to give you a warning.

remove shroud from unit & unstop drain.

Your drain for the inside unit is stopped up and the water condensate that drips off of the coils when the AC is running has no where to go, so it drips off of the collection channel and over flows to the bottom of the air handler, gravity dictates the place where it leaks. You are going to have to unstop the drain.

Yes it is normal for AC to drain on to roof as the drain holes are in base of AC unit. The time to worry is when you don't see it draining on to roof, as this indicates holes may be plugged.

check your drain hose for blockage, if it's clogged up the condensation will leak into the floor

your a/c evaporator drain is stopped up or blocked off can be seen at firewall area on passenger side looks like a short black hose coming out of firewall and turns down with nothing hooked to it if this gets restricted the blackbox under your dash fills with water and eventually leaks in floor you can try and run small piece of wire up hose to unstop but be careful not to punchure evaporator core

look for a small tube under the motor on the firewall and unplug it

Check that the drain pan is completely draining. If the drain is partialy plugged, you may get rusty water from the unit when the water level gets to the support brackets.

unstop the drain line

Under the drain pan on each side should be a small plastic drain plug they might be clogged up with debris.