No City Water Pressure

I have a 2014 Bounder Motorhome that I am dewinterizing. I connected city water to rig and have nothing coming out of the faucets. I have sufficient water coming out of hose but nothing in rig when hooked up. My guess is its the city water hookup check valve. But I took the screen off and the check valve seems to open and close freely when pushing on it. What else could it be? There are no leaks or water going anywhere else.