AIR CONDITIONER FOR VEHICLE, AND METHOD FOR OPERATING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide rational air conditioning technique capable of circulating lubricating oil to an air conditioning circuit simply at low cost in an air conditioner for a vehicle provided with the air conditioning circuit and a motor-driven compressor to circulate cooling medium to the air conditioning circuit. SOLUTION: In the air conditioning circuit 2 in this air conditioner 1 for a vehicle provided with the motor-driven compressor C, a cross charge type expansion valve 20 is provided on the inlet side of an evaporator 12. This expansion valve 20 changes an overheating degree of cooling medium. As heat exchange quantity Q between cooling medium and air conditioning air is decreased to reduce an air conditioning load, cooling medium returning to the motor-driven compressor C is controlled to be partially liquefied. At the time of a low load where circulation of lubricating oil is difficult, lubricating oil follows flow of liquefied cooling medium to be securely returned to the motor- driven compressor C.