If all of what Jumpy said is fine then the A-coil might need to be adjusted.
If superheat is high and sub-cooling is high:
Could have blockage in coil, orifice or line set.
If superheat is low and sub-cooling is low:
Orifice could be too big, there is no orifice in the unit of the orifice is stuck and refrigerant is by-passing it.
Superheat is telling you what is going on in the evaporator.
High Superheat = Starved Evaporator
Low Superheat = Flooded EvaporatorRead more