How interesting that you posted this yesterday!
Because today on our trip, I noticed that water was slowly trickling out of the door to the fresh water fill?! So I opened it and took off the cap and water was slowly coming OUT of the fill opening!
We have always been hooked to city water and don't even really use the fresh tank/pump but this seemed like it has to be the fresh tank being full to the point of coming out the fill opening.
Sure enough, the monitor shows the fresh tank as being full! The valve for normal flow/fill is in the correct position, so all I can figure is that the valve has at least partially failed and is allowing water to fill the tank unintentionally?
Any other ideas?
Sorry if this is a "hijack" of the OP thread, but I thought it was relevant due to the nature of the problem and the fact that we have the same model HC.
BTW, I turned off city water connection and am now using the pump/fresh water tank to draw down the level and avoid "overfilling".