NOVELTY - The installation (1) has a secondary loop (5) inside which heat-transfer fluid (FC) circulates. An air-conditioning loop (3) and the secondary loop interact with each other by a bi-fluid heat exchanger (19) to ensure the heat transfer between cooling fluid (FR) and the heat-transfer fluid. The air-conditioning loop comprises 3 switching bodies (15-1-15-3), where the first body is arranged between a compressor (7) and the second body that is arranged between the first body and the third body, and the third body is arranged between an outer heat exchanger (9) and an interior heat exchanger (11).    USE - Heating, ventilation and/or air-conditioning installation for cooling an electrical equipment e.g. battery, engine or electronic power box, of a motor vehicle e.g. electric or hybrid car.    ADVANTAGE - The air-conditioning loop comprises the three switching bodies, where the first body is arranged between the compressor and the second body that is arranged between the first body and the third body, and the third body is arranged between the outer heat exchanger and the interior heat exchanger, thus making the installation to be operable in all operating modes including air-conditioning, heating, de-icing and cooling modes of the equipment in a simple and effective manner while assuring modification of aerothermic parameters of a passenger compartment of the vehicle by diffusing the compartment air flow or interior air flow, at a temperature defined inside the compartment.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for implementing a heating, ventilation and/or air-conditioning installation.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic circuit diagram of a heating, ventilation and/or air-conditioning installation.    Heat-transfer fluid (FC)    Cooling fluid (FR)    Heating, ventilation and/or air-conditioning installation (1)    Air-conditioning loop (3)    Secondary loop (5)    Compressor (7)    Outer heat exchanger (9)    Interior heat exchanger (11)    Switching bodies (15-1-15-3)    Bi-fluid heat exchanger (19)