The invention relates to a heat-exchanger for an air-conditioning circuit that includes a first pipe (110) defining a path for a flow of fluid, the first pipe being spirally wound about a so-called exchanger axis (A). According to the invention, the heat exchanger (9) further includes at least one second pipe (120a, 120b) defining a path for a flow of a second fluid, said second pipe being provided against a surface of the first pipe (110)and spirally wound together with said first pipe (110) about said axis (A). The invention can be used in air-conditioning circuits operating with a super-critical coolant, in particular carbon dioxide (CO2).