A system (10) for controlling refrigerant flow in an air conditioning system employing an electrically operated valve (24) for controlling flow of refrigerant from the condenser (18) to the evaporator (30). Separate thermistors (42, 54) sense the temperature of the refrigerant entering and discharging from the evaporator. A comparison of the sensed temperatures is used to modify the control signal to the valve for maintaining proper refrigerant flow to the evaporator.