Daikin VRV III-S RXYMQ36 48PVJU, Service Manual

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SiUS34-907 Refrigerant Circuit
Refrigerant Circuit 27
1. Refrigerant Circuit
1.1 RXYMQ36 · 48P
No. in
refrigerant
system
diagram
Symbol Name Major Function
A M1C Inverter compressor (INV.)
Inverter compressor is operated on frequencies between 36Hz and 195Hz by using the
inverter.
31 steps
D
M1F
M2F
Inverter fan
Because the system is of an air heat exchange type, the fan is operated at 8-step rotation
speed by using the inverter.
E Y1E
Electronic expansion valve
(Main: EV1) While in heating operation, PI control is applied to keep the outlet superheated degree of
air heat exchanger constant.
F Y3E
Electronic expansion valve
(Subcooling: EV3) Pl control is applied to keep the outlet superheated degree of subcooling heat exchanger
constant.
G Y2S Solenoid valve (Hot gas: SVP) Prevents the low pressure from transient falling.
H Y3S
Solenoid valve (Unload circuit
SVUL)
Unloading operation of compressor.
M Y1S Four-way valve Switches the operation mode between cooling and heating.
N S1NPH High pressure sensor Detects high pressure.
O S1NPL Low pressure sensor Detects low pressure.
P S1PH
High pressure switch (For
INV. compressor) 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.
S — Fusible plug
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.
T —
Pressure regulating valve 1
(Receiver to discharge pipe)
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.
1 R1T Thermistor (Outdoor air: Ta) Detects outdoor temperature, correct discharge pipe temperature, and others.
2 R2T
Thermistor (INV. discharge
pipe: Tdi) Detects discharge pipe temperature, make the temperature protection control of
compressor, and others.
3 R3T
Thermistor
(Suction pipe1: Ts1) Detects suction pipe temperature, keeps the suction superheated degree constant in
heating operation.
4 R4T
Thermistor (Heat exchanger
deicer: Tb) Detects liquid pipe temperature of air heat exchanger, determine defrosting operation, and
others.
5 R5T
Thermistor
(Suction pipe2: Ts2)
Calculates internal temperature of compressor.
6 R6T
Thermistor (Subcooling heat
exchanger gas pipe: Tsh)
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.
7 R7T
Thermistor
(Liquid pipe: Tl)
Detects liquid pipe temperature.