Refrigerant Circuit; Rxymq36 · 48P - Daikin VRV III-S RXYMQ36 48PVJU Service Manual

SiUS34-907

1. Refrigerant Circuit

1.1 RXYMQ36 · 48P
No. in
refrigerant
Symbol
system
diagram
A M1C Inverter compressor (INV.)
M1F
D Inverter fan
M2F
Electronic expansion valve
E Y1E
(Main: EV1)
Electronic expansion valve
F Y3E
(Subcooling: EV3)
G Y2S Solenoid valve (Hot gas: SVP) Prevents the low pressure from transient falling.
Solenoid valve (Unload circuit
H Y3S
SVUL)
M Y1S Four-way valve
N S1NPH High pressure sensor
O S1NPL Low pressure sensor
High pressure switch (For
P S1PH
INV. compressor)
S — Fusible plug
Pressure regulating valve 1
T —
(Receiver to discharge pipe)
1 R1T Thermistor (Outdoor air: Ta)
Thermistor (INV. discharge
2 R2T
pipe: Tdi)
Thermistor
3 R3T
(Suction pipe1: Ts1)
Thermistor (Heat exchanger
4 R4T
deicer: Tb)
Thermistor
5 R5T
(Suction pipe2: Ts2)
Thermistor (Subcooling heat
6 R6T
exchanger gas pipe: Tsh)
Thermistor
7 R7T
(Liquid pipe: Tl)
Refrigerant Circuit
Name
Inverter compressor is operated on frequencies between 36Hz and 195Hz by using the
inverter.
31 steps
Because the system is of an air heat exchange type, the fan is operated at 8-step rotation
speed by using the inverter.
While in heating operation, PI control is applied to keep the outlet superheated degree of
air heat exchanger constant.
Pl control is applied to keep the outlet superheated degree of subcooling heat exchanger
constant.
Unloading operation of compressor.
Switches the operation mode between cooling and heating.
Detects high pressure.
Detects low pressure.
In order to prevent the increase of high pressure when a malfunction occurs, this switch is
activated at high pressure of 580psi or more to stop the compressor operation.
In order to prevent the increase of pressure when abnormal heating is caused by fire or
others, the fusible part of the plug is molten at a temperature of 158 to 167°F to release
the pressure into the atmosphere.
This valve opens at a pressure of 580 psi for prevention of pressure increase, thus
resulting in no damage of functional parts due to the increase of pressure in transportation
or storage.
Detects outdoor temperature, correct discharge pipe temperature, and others.
Detects discharge pipe temperature, make the temperature protection control of
compressor, and others.
Detects suction pipe temperature, keeps the suction superheated degree constant in
heating operation.
Detects liquid pipe temperature of air heat exchanger, determine defrosting operation, and
others.
Calculates internal temperature of compressor.
Detectst gas pipe temperature on the evaporation side of subcooling heat exchanger,
keep the superheated degree at the outlet of subcooling heat exchanger constant, and
others.
Detects liquid pipe temperature.
Major Function
Refrigerant Circuit
27