The present invention relates to an air-conditioning circuit (1) for a motor vehicle, which carries a refrigerant and includes: a compressor (3); a first heat exchanger (5); an ejector (7) comprising:a first refrigerant intake (7a) and a second refrigerant intake (7b), and a refrigerant outlet (7c); a phase-separation device (9) including: a refrigerant intake (9a), a first outlet (9b) for refrigerant in gaseous phase, and a second outlet (9c) for refrigerant in liquid phase; an expansion device (11); and a second heat exchanger (13), the air-conditioning circuit (1) also including a bypass duct (A) connecting a first junction point (15a) and a second junction point (15b), said bypass duct (A) including a third heat exchanger (17).