[Fulltiming]

Moving the control rod up would tell the valve that the coach body was sitting too low on that side and needed more air. Moving the control rod down would tell the valve that the coach body was too high and needed to exhaust some air. There is only one position at which it thinks the body is level and neither needs to take on additional air nor exhaust air. I am not familiar with the Valid height control valves but the HWH height control valves have a plastic body and I have had them develop a crack in the valve body resulting in a MAJOR air leak. I am not surprised with the engine off and the power to the 120 volt air compressor turned off that it would start to sag on that side if there were an air leak in the solenoid, the valve or the air bag. On the HWH system, when you take the leveling system out of level and back into travel mode, the solenoids that take air into the travel height valves are opened up so any leak beyond the travel solenoids would cause the side to droop.

I would look closely at the ride height valve body for a crack.