I don't want to hijack this thread, but I have an identical problem. We had the AC replaced last October by a company that is no longer in existence. When the tech installed the unit he did not connect the drain hose on the coach to the drain on the AC unit. I'll have to get a 12" extension hose to fix. When they replace the unit I did not receive an installation guide. Can someone provide me with a link to the manufacturer.
Coleman Mach 8 13.5 with heat pump and conditioner #62614 On Edit, I just found the manual.
Coleman Mach In stall GuideI have been following this thread hoping for a solution, and consequently I over tightened the hold down screws(hopefully loosening them will not cause permanent damage to the seal).