To provide a method and an apparatus for controlling an electronic expansion valve for controlling the degree of pinch of a cooler and sustaining the delivery degree of superheat of a compressor used in a refrigerating machine or a heat pump.

An electronic expansion valve EXV for use in the refrigeration cycle 10 of a heat pump or a refrigerating machine is controlled to sustain the degree of pinch at a minimum level so that appropriate heat exchanging performance of a flooded cooler are ensured by monitoring the difference between the fluid temperature CFT and the saturated suction temperature SST of a cooler. In order to protect a compressor 40 against formation of slug from liquid, delivery degree of superheat DSH is monitored. When it is lower than an expected value, opening of the EXV is adjusted. A controller 15 monitors specified variables of an apparatus used for determining the optimal position of the EXV for optimizing the performance of the apparatus, the DSH and the refrigerant load.