Refrigerant circuit expansion valve control

A method is for operating an expansion valve in a refrigerant circuit that includes a compressor, a condenser, the expansion valve, an evaporator, and a working fluid. The method includes determining a modified subcooling value based on a condenser working fluid discharge temperature, a condenser discharge subcooling setpoint, and one or more of a compressor discharge temperature and an evaporator approach temperature. The method also includes adjusting the expansion valve according to the modified subcooling value. A refrigerant circuit for a heating, ventilation, air conditioning, and refrigeration system includes a controller configured to operate the expansion valve according to a modified subcooling value.