METHOD OF OPERATING A VEHICLE AIR-CONDITIONING SYSTEM HAVING A CENTRIFUGAL-TYPE ELECTRIC REFRIGERANT COMPRESSOR

An air conditioning system for an electric vehicle includes a refrigerant E-compressor made up of a centrifugal compressor and an electric motor for driving the compressor. The housing of the compressor defines a coolant passage for liquid coolant. A coolant unit pumps liquid coolant through the coolant passage during normal AC system operation to cool the motor. A method for preventing or mitigating harmful effects of liquid refrigerant being ingested by the compressor includes determining whether liquid refrigerant is likely present in the compressor inlet; if so, a heating unit raises the temperature of the liquid coolant to thereby heat and evaporate any liquid refrigerant before starting the compressor. Once the danger of liquid refrigerant is passed, the compressor is started and the heating unit is deactivated.