Refrigerant Circuit Si34-60344 Refrigerant Circuit1. Refrigerant Circuit1.1 RX(Y)MQ4 / 5 / 6PNo. inrefrigerantsystemdiagramSymbol Name Major FunctionA M1C Inverter compressor (INV) Inverter compressor is operated on frequencies between 36 Hz and 195 Hz by usingthe inverter.31 stepsD M1FM2F Inverter fan Since the system is of air heat exchanging type, the fan is operated at 8-step rotationspeed by using the inverter.E Y1E Electronic expansion valve(Main: EV1) While in heating operation, PI control is applied to keep the outlet superheated degreeof air heat exchanger constant.F Y3E Electronic expansion valve(Subcool: EV3) Pl control is applied to keep the outlet superheated degree of subcooling heatexchanger constant.G Y2S Solenoid valve (Hot gas: SVP) Used to prevent the low pressure from transient falling.H Y3S Solenoid valve (Unload circuitSVUL) Used to the unloading operation of compressor.M Y1S Four way valve Used to switch the operation mode between cooling and heating.N S1NPH High pressure sensor Used to detect high pressure.O S1NPL Low pressure sensor Used to detect low pressure.P S1PH HP pressure switch (For INVcompressor)In order to prevent the increase of high pressure when a malfunction occurs, thisswitch is activated at high pressure of 4.0 MPa or more to stop the compressoroperation.S — Fusible plug In order to prevent the increase of pressure when abnormal heating is caused by fireor others, the fusible part of the plug is molten at a temperature of 70 to 75°C torelease the pressure into the atmosphere.T — Pressure regulating valve 1(Receiver to discharge pipe)This valve opens at a pressure of 4.0 MPa for prevention of pressure increase, thusresulting in no damage of functional parts due to the increase of pressure intransportation or storage.1 R1T Thermistor (Outdoor air: Ta) Used to detect outdoor temperature, correct discharge pipe temperature, and others.2 R2T Thermistor (INV dischargepipe: Tdi) used to detect discharge pipe temperature, make the temperature protection control ofcompressor, and others.3 R3T Thermistor(Suction pipe1: Ts1) used to detect suction pipe temperature, keep the suction superheated degreeconstant in heating operation, and others.4 R4T Thermistor (Heat exchangerdeicer: Tb)Used to detect liquid pipe temperature of air heat exchanger, determine defrostingoperation, and others.5 R5T Thermistor(Suction pipe2: Ts2) Used to the calculation of an internal temperature of compressor etc.6 R6T Thermistor (Subcooling heatexchanger gas pipe: Tsh) Used to control of subcooling electronic expansion valve.7 R7T Thermistor(Liquid pipe: Tl) Used to detect refrigerant over charge in check operation, and others.
