hubbard 460 2006

have a issue with a 460 r4o4a single phase stby the evaporator is iceing heavily in the top 2 to 3 loops the tev is iced heavy and the little check valve beside the tev its a two line system to but below these loops no iceing not even sweating of coil on stby the suction side is on the floor ie 3 psi 160 head ony one condensor fan working as not enough head on engine suction better at 20 psi but still iceing top part of coil new tev cpr is set up well the gas level is good why is the tev and hot gas check valve iceing so hard is the check valve bleeding back and alowingthe refrigerant to circle around superheat just cant ajust it orifice is new any ideas unit has always pulled good temp running tm 15s at mo evap fan running good speed and corect way around df set up as norm every hr any ideas

does the compressor seem ok,does it pump down sounds like a weak compressor with that h/p so low?.

found the check valve seat on evap leaking by replaced it and running back to 25 psi suction never had one do this pulls temp well now ta charlie