A vapor compression system comprising: a compressor comprising: a housing assembly having a suction port and a discharge port and a motor compartment; an electric motor having a stator within the motor compartment and a rotor within the stator, the rotor being mounted for rotation about a rotor axis; one or more working elements coupled to the rotor to be driven by the rotor in at least a first condition so as to draw fluid in through the suction port and discharge said fluid out from the discharge port; and one or more bearings (66, 68) supporting the rotor and/or the one or more working elements; a first heat exchanger coupled to the discharge port to receive refrigerant driven in a downstream direction in the first operational condition of the compressor; an expansion device downstream of the first heat exchanger; a second heat exchanger downstream of the expansion device and coupled to the suction port to return refrigerant in the first operating condition; and a purge unit having: a vapor inlet line for receiving a refrigerant flow from the first heat exchanger; and a return line (414, 417A, 417B) for returning a contaminant-depleted refrigerant flow, wherein: a supply flowpath (407A, 407B) extends from the purge unit via the return line (417A, 417B); characterised in that the compressor comprises one or more bearing feed passages coupled to the bearings and forming the supply flowpath to the bearings to pass refrigerant to the bearings to lubricate the bearings. a compressor comprising: a housing assembly having a suction port and a discharge port and a motor compartment; an electric motor having a stator within the motor compartment and a rotor within the stator, the rotor being mounted for rotation about a rotor axis; one or more working elements coupled to the rotor to be driven by the rotor in at least a first condition so as to draw fluid in through the suction port and discharge said fluid out from the discharge port; and one or more bearings (66, 68) supporting the rotor and/or the one or more working elements; a housing assembly having a suction port and a discharge port and a motor compartment; an electric motor having a stator within the motor compartment and a rotor within the stator, the rotor being mounted for rotation about a rotor axis; one or more working elements coupled to the rotor to be driven by the rotor in at least a first condition so as to draw fluid in through the suction port and discharge said fluid out from the discharge port; and one or more bearings (66, 68) supporting the rotor and/or the one or more working elements; a first heat exchanger coupled to the discharge port to receive refrigerant driven in a downstream direction in the first operational condition of the compressor; an expansion device downstream of the first heat exchanger; a second heat exchanger downstream of the expansion device and coupled to the suction port to return refrigerant in the first operating condition; and a purge unit having: a vapor inlet line for receiving a refrigerant flow from the first heat exchanger; and a return line (414, 417A, 417B) for returning a contaminant-depleted refrigerant flow, wherein: a supply flowpath (407A, 407B) extends from the purge unit via the return line (417A, 417B); characterised in that the compressor comprises one or more bearing feed passages coupled to the bearings and forming the supply flowpath to the bearings to pass refrigerant to the bearings to lubricate the bearings. a vapor inlet line for receiving a refrigerant flow from the first heat exchanger; and a return line (414, 417A, 417B) for returning a contaminant-depleted refrigerant flow, a supply flowpath (407A, 407B) extends from the purge unit via the return line (417A, 417B); characterised in that the compressor comprises one or more bearing feed passages coupled to the bearings and forming the supply flowpath to the bearings to pass refrigerant to the bearings to lubricate the bearings.