Do you have pumps or just a tube?
If you don't have a pump you might want to install one.
See if this
Mine came with the pumps. There is a tube run under my roof to the bottom of the back cap. As far as I can tell the pump runs whenever the A/C runs so the water basically dribbles out except when it first comes on and accumulated condensation comes dumping out in a torrent.
It does not pump it dry but I have no evidence of it splashing out or draining on the roof at all or inside the duct work.
Mine has a strainer bug shield on the tube exit. If you don't have anything protecting the tube end then maybe a bug built a nest in there and clogged it. If you do make sure it is clean.
It is pretty easy to pull the A/C cover off, but you will need a long 1/4 inch drive extension or very nimble fingers. Once you have the evaporator cover off you can look at the pump and see if it is clogged.