There are several notches or holes around the base of the roof unit to allow drainage. They need to be kept clear of debris. Another thing that could e happening - if you are running your fan on low speed there may be ice build-up on the coils preventing proper drainage. High speed keeps the air moving and prevents ice from forming.
2006 Crossroads Cruiser CF32BL | 2012 Ford F350 Crew Cab Dually
Been to all 48 lower continental states once! Starting over...