Refrigerant Circuit SiE39-40450 Refirgerant Circuit1. Refrigerant Circuit1.1 RXYQ5M (*Products after January, 2004)Note: Please refer the refrigerant circuit for products before December, 2003 to service manualSi39-302.No. inrefrigerantsystemdiagramSymbol Name Major FunctionA M1C Inverter compressor (INV)Inverter compressor is operated on frequencies between 52 Hz and 210 Hz by usingthe inverter. The number of operating steps is as follows when Inverter compressor isoperated.RXYQ5M : 20 stepsD M1F 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.G Y1S Solenoid valve (Hot gas: SVP) Used to prevent the low pressure from transient falling.J Y2S Solenoid valve (Receiver gasdischarging: SVG) Used to collect refrigerant to receiver.K Y4S Solenoid valve (Injection) Used to cool the compressor by injecting refrigerant when the compressor dischargetemperature is high.M Y3S 4-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 3.8 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 2 to 2.7 MPa for prevention of pressure increase,thus resulting 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 (Suction pipe: Ts) Used to detect suction pipe temperature, keep the suction superheated degreeconstant in heating operation, and others.3 R3T Thermistor (INV dischargepipe: Tdi) Used to detect discharge pipe temperature, make the temperature protection control ofcompressor, 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 (Sub-cooling heat-exchanger outlet) Used to judge the refrigerant overcharge at the check operation.
