Daikin VRV II RXYQ8MY1K, Service Manual

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Refrigerant Circuit Si39-502A
44 Refirgerant Circuit
1. Refrigerant Circuit
1.1 RXYQ8M, 10M
No. in
refrigerant
system
diagram
Symbol Name Major Function
A M1C Inverter compressor (INV) Inverter compressor is operated on frequencies between 52 Hz and 210 Hz
by using the inverter, while Standard compressor is operated with
commercial power supply only. The number of operating steps is as follows
when Inverter compressor is operated in combination with Standard
compressor.
RXYQ8, 10M: 37 steps
B M2C
Standard compressor 1
(STD1)
D M1F Inverter fan
Since the system is of air heat exchanging type, the fan is operated at 9-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 Y2E
Electronic expansion valve
(Subcool: EV2) PI control is applied to keep the outlet superheated degree of subcooling
heat exchanger constant.
G Y1S
Solenoid valve (Hot gas:
SVP)
Used to prevent the low pressure from transient falling.
J Y2S
Solenoid valve (Receiver
gas discharging: SVG)
Used to collect refrigerant to receiver.
L Y3S
Solenoid valve (Non-
operating unit liquid pipe
closing: SVSL)
Used to prevent the accumulation of refrigerant in non-operating outdoor
units in the case of multi-outdoor unit system.
M Y4S 4-way valve Used to switch the operation mode between cooling and heating.
N
S1NP
H
High pressure sensor Used to detect high pressure.
O
S1NP
L
Low pressure sensor Used to detect low pressure.
P S1PH
HP 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 4.0 MPa or more to stop the
compressor operation.
Q S2PH
HP pressure switch (For
STD compressor 1)
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 70 to 75°C to release the pressure into the atmosphere.
U —
Pressure regulating valve
2 (Liquid pipe to receiver)
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 in transportation or storage.
V — Piping heat exchanger Used to heat the gas refrigerant from the liquid receiver.
W — Capillary tube
Used to return the refrigerating oil separated through the oil separator to the
INV compressor.
X — Capillary tube
Used to return the refrigerating oil separated through the oil separator to the
STD1 compressor.
Y — Capillary tube Used to add the refrigerant flow capacity to Y1E.
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
degree constant in heating operation, and others.
3 R31T
Thermistor (INV discharge
pipe: Tdi)
Used to detect discharge pipe temperature, make the temperature protection
control of compressor, and others.
4 R32T
Thermistor (STD1
discharge pipe: Tds1)
6 R4T
Thermistor (Heat
exchanger deicer: Tb) Used to detect liquid pipe temperature of air heat exchanger, determine
defrosting operation, and others.
7 R5T
Thermistor (Subcooling
heat exchanger gas pipe:
Tsh) Used to detect 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.
8 R6T
Thermistor (Receiver
outlet liquid pipe: Tl)
Used to detect receiver outlet liquid pipe temperature, prevent the drift
between outdoor units while in heating operation in the case of multiple-
outdoor-unit system, and others.