Abstract: SA four way slide valve comprises a plunger (122, 51) connected to a slider (113, 45) and a solenoid coil (12, 55) for driving the plunger thereby to switch the four way valve between room-heating and room-cooling, and further, by inserting a demagnetizable permanent magnet (54) in series to magnetic circuit of the plunger (51) and a stator core (52) and magnetizing and demagnetizing the permanent magnet for switching operation of the refrigerant circuit, the hitherto necessitated retention current for the plunger is eliminated, thereby eliminating undesirable noises hitherto generated by a pilot valve used for switching the slide valve, and further saving the power consumption.