Refrigerant Circuit; Outdoor Units; Refrigerant Circuit Part - Daikin E-Series Service Manual

Refrigerant Circuit

1. Refrigerant Circuit

1.1

Outdoor Units

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
(Subcool: EV3)
G Y2S Solenoid valve (Hot gas: SVP) Used to prevent 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
HP pressure switch (For INV
P S1PH
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)
50
Name
Inverter compressor is operated on frequencies between 36 Hz and 195 Hz by using
the inverter.
31 steps
Since the system is of air heat exchanging 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.
Used to the unloading operation of compressor.
Used to switch the operation mode between cooling and heating.
Used to detect high pressure.
Used to detect low pressure.
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.
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.
This valve opens at a pressure of 4.0 MPa for prevention of pressure increase, thus
resulting in no damage of functional parts due to the increase of pressure in
transportation or storage.
Used to detect outdoor temperature, correct discharge pipe temperature, and others.
used to detect discharge pipe temperature, make the temperature protection control of
compressor, and others.
used to detect suction pipe temperature, keep the suction superheated degree
constant in heating operation, and others.
Used to detect liquid pipe temperature of air heat exchanger, determine defrosting
operation, and others.
Used to the calculation of an internal temperature of compressor etc.
Used to control of subcooling electronic expansion valve.
Used to detect refrigerant over charge in check operation, and others.
Major Function
SiENBE18-621
Refrigerant Circuit