That line is like on a refrigerator water line- so you can pull out the frige and clean behind, only this is so you can pick up odu and stuff it in door and move trailer.
Then you don't need hvac guy to hook it back up afetr you get the tralier to new site- isn't that a great idea?
What does this have to do with Trane? They only sold the packaged unit, does not sound like they installed. A bad installation has nothing to do with the Manufacturer. I feel Trane is at the top of the HVAC chain and will be for many years to come.