Try a fan on the unit
Andrew:Think about opening the compartment and place an AC fan on the unit. This should give you some indication of it is an internal or external problem.I would agree that if you have a filter, you definetly want to be sure that it is clear.This is one thing that I really like about our Isotherm SP unit. It is water cooled and no fan. The coolant runs through a coil in the galley sink thru hull. No need for a fan or a strainer.