Method for operating a refrigerating cycle and a refrigerating cycle

An electronic expansion valve (3) of a refrigeration cycle is controlled such that during normal operation, refrigerant is always in a superheated state at the outlet of an evaporator (4). Then the refrigerant is periodically forced by a superheat control device (6) to have negative superheat for a predetermined time. During normal operation, the refrigerant sucked into the variable displacement compressor (1) always has superheat. The refrigeration cycle operates with a high coefficient of performance. The engine driving the compressor (1) operates at high fuel efficiency. The refrigerant is temporarily controlled so as to have negative superheat. Then lubricating oil retained in the evaporator (4) flows into the compressor (1), preventing that the compressor (1) suffers from seizing due to oil shortage.