a passenger compartment;

an air conditioner containing a refrigeration circuit operated using a refrigerant, said refrigeration circuit having a condenser with an associated condenser fan for conveying cooling air, and an evaporator, belonging to an air treatment part of said air conditioner, for controlling a temperature of supply air being conveyed by means of a supply air fan into said passenger compartment of the passenger transport vehicle, said air conditioner having a common partition wall and a flow channel for the cooling air and a flow channel for the supply air being fluidically separated from one another by said common partition wall, said common partition wall having a closable degassing device being switched between a closed state for normal operation of said air conditioner and an open state for emergency operation of said air conditioner, in which said closable degassing device fluidically connects said flow channel for the cooling air and said flow channel for the supply air directly together; and

a detector of the refrigerant disposed in a region of the passenger transport vehicle to which the supply air is admitted, said detector connected via signals to said closable degassing device such that, when said detector detects the refrigerant, said detector initiates actuation of said closable degassing device so that said closable degassing device assumes the open state.