Too long, not sure what model coach you have but here is what I found on our Essex. The drain for the window channel did not have a hole drilled for the water to drain out. For lack of knowledge as to what to call it I call it a trough that is to collect the water and let it drain. Newmar failed to put a hole in the trough. There is a hose attached to the trough but no hole. If this is your issue you will need to pull the panel beside the drivers seat, remove the plastic sheeting, find the drain hose and drill a hole so the water will drain. There is a TSB from Newmar concerning certain year coaches. Hope this helps.
2009 Essex - Bordeaux
2016 Mini Cooper S
2016 Moto Guzzi Stornello 2016 Ducati Monster 821 on a Hydralift