Reversible air-conditioning circuit in which a refrigerant circulates and that includes: • a main loop (A) including, in the direction of circulation of the refrigerant, a compressor , a water condenser jointly connected to an auxiliary circuit in which a heat-transfer fluid circulates, a first expansion device , an external evaporator-condenser suitable for being passed through by an external air flow , a second expansion device , and an evaporator suitable for being passed through by an internal air flow , • a first bypass branch (B) including an internal condenser suitable for being passed through by an internal air flow , said first bypass branch (B) connecting a first junction point arranged downstream of the water condenser , between said condenser and the first expansion device , to a second junction point arranged upstream of the second expansion device , between the external evaporator-condenser and said second expansion device , • a second bypass branch (C) connecting a third junction point arranged downstream of the external evaporator-condenser , between said external evaporator-condenser and the second junction point , to a fourth junction point arranged downstream of the evaporator , between said evaporator and the compressor , and • a third bypass branch (D) connecting a fifth junction point arranged downstream of the third junction point , between said third junction point and the second junction point , to a sixth junction point arranged downstream of the first junction point , between said first junction point and the first expansion device , • the main loop (A) including an internal heat exchanger configured to allow heat exchanges between the refrigerant at separate pressures, said internal heat exchanger being arranged both between the fifth and second junction points and between the fourth junction point and the compressor . • a main loop (A) including, in the direction of circulation of the refrigerant, a compressor , a water condenser jointly connected to an auxiliary circuit in which a heat-transfer fluid circulates, a first expansion device , an external evaporator-condenser suitable for being passed through by an external air flow , a second expansion device , and an evaporator suitable for being passed through by an internal air flow , • a first bypass branch (B) including an internal condenser suitable for being passed through by an internal air flow , said first bypass branch (B) connecting a first junction point arranged downstream of the water condenser , between said condenser and the first expansion device , to a second junction point arranged upstream of the second expansion device , between the external evaporator-condenser and said second expansion device , • a second bypass branch (C) connecting a third junction point arranged downstream of the external evaporator-condenser , between said external evaporator-condenser and the second junction point , to a fourth junction point arranged downstream of the evaporator , between said evaporator and the compressor , and • a third bypass branch (D) connecting a fifth junction point arranged downstream of the third junction point , between said third junction point and the second junction point , to a sixth junction point arranged downstream of the first junction point , between said first junction point and the first expansion device , • the main loop (A) including an internal heat exchanger configured to allow heat exchanges between the refrigerant at separate pressures, said internal heat exchanger being arranged both between the fifth and second junction points and between the fourth junction point and the compressor . <EOS>