Vehicle conditioning system

Vehicle air-conditioning system, in particular CO₂ air conditioner, the refrigerant cycle of which comprises the following components: a compressor, a refrigerant cooler, an internal heat exchanger between the refrigerant-cooler side and the evaporator side, an expansion valve, and an evaporator. To switch the air-conditioning system from cooling-mode operation to heating-mode operation, between the compressor and the refrigerant cooler there is integrated an auxiliary heat exchanger corresponding to a cooling circulation on the engine side, such that downstream of the auxiliary heat exchanger there is disposed an expansion valve by means of which during heating-mode operation the refrigerant can be throttled to a lower pressure.