A servicing device and method for operating a servicing device for vehicle air-conditioning systems in particular for the self-cleaning thereof, the servicing device is equipped with an emptying device and a filling device for the drawing off of the refrigerant/compressor oil mixture from the refrigerant circuit system of a vehicle air-conditioning system and for the refilling of the vehicle air-conditioning system with refrigerant and compressor oil. A vacuum pump is used for the residual emptying of the refrigerant circuit system of the vehicle air-conditioning system and/or of the servicing device. An at least partially evacuated flushing agent tank is connected directly or indirectly via a connecting line with at least one of the high pressure servicing connection connectors of the servicing device and/or the subsequent pressure hoses and/or the switchover valve block and that a fluidic further connection takes place to the refrigerant reservoir which is under increased refrigerant pressure.