Faulty water heater
I purchased a 2018 Little Guy Mini Max RV Trailer equipped with a Dometic model #GC6AA-10E gas/electric hot water heater controlled by a Zhongding circuit board #91346 B 2318 12663.The water heater suddenly became inoperative in both gas and electric modes after 2yrs. There were no external shorts/faults, the 2amp fuse was intact, and the fault seemed isolated to the circuit board itself which was emitting an abnormal, low volume, high pitched buzz/squeal. Online research revealed multiple, similar instances/occurrences of this circuit board failure across all fleets and RV types. Dometic is aware of the issue, was helpful, and sent a replacement circuit board since the faulty board's serial# was in the bad lot. It is very easy to install by owner, and voila, the heater works in both modes!