Refrigeration cycle device for vehicle

A refrigeration method comprising operating a refrigeration cycle device for a vehicle,

• wherein the operating comprises applying a refrigerant as an alternative refrigerant for R1234yf alone,
• wherein a first equipment designed for operation using R1234yf alone is operated using the alternative refrigerant, optionally with changes of a few parts and adjustment of the first equipment, or
• a second equipment designed for operation using the alternative refrigerant is operated for the same use as an existing use with R1234yf by using the alternative refrigerant,
• wherein:
• the refrigeration cycle device comprises a refrigerant circuit,
• the refrigerant circuit comprises a compressor, a condenser, a decompressor, and an evaporator;
• the refrigerant is sealed in the refrigerant circuit,
• the refrigerant comprises at least trans-1,2-difluoroethylene (HFO-1132(E)) and 2,3,3,3-tetrafluoropropene (HFO-1234yf), and
• the refrigerant comprises HFO-1132(E) and HFO-1234yf in such amounts that the sum of HFO-1132(E) and HFO-1234yf is 99.7 mass % or more.