Probable Cause:
Incorrect size of distributor and/or orifice.
Liquid short-circuits thru unequally loaded passes and throttles the valve before all passes receive sufficient refrigerant.
Remedy:
Distributor tubes must be of equal dimension and length.
Liquid traps should be avoided when mounting the distributor tubes.
NOTE: at proper load there should be no more than SOF difference between any two circuits as they enter the header.