An air conditioner includes a compressor, first and second heat exchangers connected with high pressure piping, low pressure piping connecting the second heat exchanger to a compressor suction port, a pressure reducing mechanism arranged to reduce pressure in the high pressure piping, a bypass passageway, a vessel connected to the bypass passageway, and first and second openingclosing mechanisms. A current first parameter value is determined from an index corresponding to at least the first parameter. The radius of curvature of the guiding lines of the conical surfaces of the projections edges and of the slots bottoms can be embodied in such a way that they tend to infinity; at least one connecting part can be embodied in the form of a through-thickness composite part. A conveyor conveys the leg part past the skinning rolls and after that past the knives.