Schematic Diagram of Refrigerant
| No. | Part name | Symbol | (Electrical symbol) | Function | |
| Outdoor unit sensor | Outdoor thermistor | Ta | (R1T) | Used to detect outdoor temperature, thus compensating discharge pipe temperature and others. | |
| Suction pipe thermistor | Ts | (R2T) | Used to detect suction pipe temperature, thus conducting constant control of the suction superheated degree in heating operation. | ||
| Discharge pipe thermistor (INV) | Tdi | (R31T) | Used to detect discharge pipe temperature, thus conducting the protection control of compressor temperature. | ||
| Discharge pipe thermistor (STD1) | Tds1 | (R32T) | |||
| Discharge pipe thermistor (STD2) | Tds2 | (R33T) | |||
| Heat exchanger deicer thermistor | Tb | (R4T) | Used to detect the liquid pipe temperature of air heat exchanger, thus making judgment of defrosting operation. | ||
| Subcooling heat exchanger gas pipe thermistor | Tsh | (R5T) | Used to detect gas pipe temperature on the evaporation side of subcooling heat exchanger, thus conducting the constant control of outlet superheated degree of the subcooling heat exchanger. | ||
| Receiver outlet liquid pipe thermistor | Tl | (R6T) | Used to detect outlet liquid pipe temperature of the receiver, thus conducting the preventive control of drift between outdoor units in heating operation on the multi outdoor unit system. | ||
| Oil equalizer pipe thermistor | To | (R7T) | Used to detect oil equalizer pipe temperature, thus detecting the opening / closing operation of the stop valve for oil equalizer pipe. | ||
| N | High-pressure thermistor | Pc, Tc | (S1NPH) | Used to detect high pressure. | |
| O | Low-pressure thermistor | Pe, Te | (S1NPL) | Used to detect low pressure. | |
| Indoor unit sensor | Discharge air thermistor | Tr | (R1T) | Used for thermostat control and the compensation of electronic expansion valve control. | |
| Liquid pipe thermistor | Tl | (R2T) | Used to control superheated degree (SH = Tg – TI) in cooling operation. • Used to freeze-up prevention control. Used to control subcooled degree (SC = Tc – TI) in heating operation. • Used for hot start reset (34°C). | ||
| Gas pipe thermistor | Tg | (R3T) | Used to control superheated degree (SH = Tg – TI) in cooling operation. | ||
| Components of outdoor unit | A | INV compressor | INV | (M1C) | Inverter compressors are driven by inverter at a frequency in the range of 52 Hz to 210 Hz. STD compressors are only operated with commercial power supply. The following section shows the number of operation steps in combined use of the inverter and STD compressors. RXY(Q)5M : 20 steps RXY(Q)8, 10, 12M : 29 steps RXY(Q)14, 16M : 35 steps |
| B | STD compressor 1 | STD1 | (M2C) | ||
| C | STD compressor 2 | STD2 | (M3C) | ||
| D | INV fan | — | (M1F) | This inverter fan operates at revolution speed in eight steps by inverter drive for heat exchange with the air heat exchanger. | |
| E | Electronic expansion valve (Main) | EV1 | (Y1E) | Used for PI control in heating operation so that the outlet superheated degree of the air heat exchanger will be kept constant. | |
| F | Electronic expansion valve (Subcooling) | EV2 | (Y2E) | Used for PI control so that the outlet superheated degree of the subcooling heat exchanger will be kept constant. | |
| G | Solenoid valve (Hot gas) | SVP | (Y1S) | Used to prevent the transitional drop of low pressure. | |
| H | Solenoid valve (Oil equalizer) | SVO | (Y2S) | Used to conduct oil equalization between outdoor units on the outdoor unit multi system. | |
| I | Solenoid valve (Receiver gas inlet) | SVL | (Y3S) | Used to maintain high pressure in cooling operation with low outdoor temperature. Furthermore, used to prevent the refrigerant from accumulating in outdoor units in stop mode on the multi outdoor unit system. | |
| J | Solenoid valve (Receiver gas purging) | SVG | (Y4S) | Used to recover the refrigerant into the receiver. |
| No. | Part name | Symbol | (Electrical symbol) | Function | ||
| Components of outdoor unit | K | Solenoid valve (Non- operating unit gas discharging) | SVSG | (Y5S) | On the outdoor unit multi system, used to prevent the refrigerant from accumulating in outdoor units in stop mode. | |
| L | Solenoid valve (Non- operating unit liquid pipe closing) | SVSL | (Y6S) | On the outdoor unit multi system, used to prevent the refrigerant from accumulating in outdoor units in stop mode. | ||
| M | Four way valve | — | (Y7S) | Used to switch the unit to cooling operation or heating operation. | ||
| P | High-pressure switch (For INV compressor) | — | (S1PH) | In order to avoid the increase in high pressure while in malfunction, these switches are actuated at a pressure of 3.8MPa or more to stop the unit. (2.7 MPa for R22 unit) | ||
| Q | High-pressure switch (For STD compressor 1) | — | (S2PH) | |||
| R | High-pressure switch (For STD compressor 2) | — | (S3PH) | |||
| S | Fusible plug | — | — | In order to avoid increase in pressure at abnormal hating due to fire, the fusible part melts at a temperature of 70 to 75°C, thus relieving pressure into atmosphere. | ||
| T | Pressure regulating valve 1 (Receiver to Discharge pipe) | — | — | In order to prevent damage to functional parts due to increase in pressure in transport or storage, these valves open at pressure of 2 to 2.7MPa, thus avoiding the increase in pressure. (1.5 ~ 2.0 MPa for R22 unit) | ||
| U | Pressure regulating valve 2 (Liquid pipe to Receiver) | — | — | |||
| V | Pressure regulating valve 3 (Oil equalizer pipe to Discharge pipe) | — | — | |||
| Components of indoor unit | X | Indoor unit heat exchanger | — | — | This heat exchanger serves as an evaporator while in cooling operation or a condenser while in heating operation (air cooling). | |
| Y | Indoor unit electronic expansion valve | — | (Y1E) | Used to control the superheated degree (SH = Tg – TI) in cooling operation or subcooled degree (SC = Tc – TI) in heating operation. This valve slightly opens (i.e., 240 pls) with thermostat OFF (compressor ON) in heating operation, thus preventing the accumulation of oil. |
