Refrigerant Circuit Part; Refrigerant Circuit; Outdoor Unit - Daikin RMXS-L Series Service Manual

Refrigerant Circuit

1. Refrigerant Circuit
1.1

Outdoor Unit

No. in
Symbol
diagram
A M1C Compressor motor
M1F
D Fan motor
M2F
Electronic expansion valve
E Y1E
(Main)
Electronic expansion valve
F Y3E
(Subcooling)
Solenoid valve
G Y2S
(Hot gas bypass)
H Y3S Solenoid valve (Unload circuit) Used for the unloading operation of the compressor.
M Y1S Four way valve
N S1NPH High pressure sensor
O S1NPL Low pressure sensor
P S1PH High pressure switch
S — Fusible plug
Pressure regulating valve
T —
(Receiver to discharge pipe)
Thermistor
1 R1T
(Outdoor temperature: Ta)
Thermistor
2 R2T
(Discharge pipe: Tdi)
Thermistor
3 R3T
(Suction pipe 1: Ts1)
Thermistor
4 R4T
(Outdoor heat exchanger: Tb)
Thermistor
5 R5T
(Suction pipe 2: Ts2)
Thermistor (Subcooling heat
6 R6T
exchanger gas pipe: Tsh)
7 R7T Thermistor (Liquid pipe: Tl)
Filter
Accumulator
42
Name
The 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
the air heat exchanger constant.
PI control is applied to keep the outlet superheated degree of the subcooling heat
exchanger constant.
Used to prevent the low pressure from temporary falling.
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 an error occurs, this switch is activated
at high pressure of 4.0 MPa (1338 ftAq) or more to stop the compressor operation.
In order to prevent the increase of pressure when abnormal heating is caused by fire, etc., the fusible part
of the plug melts at a temperature of 70 ~ 75°C (158 ~ 167°F) to release the pressure into the atmosphere.
This valve opens at a pressure of 4.0 MPa (1338 ftAq) to prevent pressure increase, thus protecting
functional parts from damage due to the increase of pressure in transportation or storage.
Used to detect outdoor temperature, correct discharge pipe temperature, etc.
Used to detect discharge pipe temperature, for temperature protection control of the
compressor, etc.
Used to detect suction pipe temperature, keep the suction superheated degree constant in
heating operation, etc.
Used to detect liquid pipe temperature of the outdoor heat exchanger, determine
defrosting operation, etc.
Used to calculate the internal temperature of the compressor etc.
Used to control the subcooling electronic expansion valve.
Used to detect refrigerant overcharge in check operation, etc.
Electronic
expansion valve
Double pipe
heat exchanger
(F)
(7)
(6)
Service port
Low pressure
sensor
Filter
Capillary
tube
(5)
Compressor
(A)
Stop valve (with service port on field piping side φ 7.9 mm ( φ 5/16 inch) flare connection)
Major Function
Electronic
Fusible
expansion
plug
valve
(S)
Filter
(E)
(T)
Heat exchanger
Pressure
regulating valve
(3)
(D) (D)
Four way
valve
(M)
(O)
(H)
Solenoid
Capillary
valve
tube
Filter
Filter
(2)
Capillary
tube
High pressure
switch
(P)
(4)
(1)
Service port
(N) High pressure
S1NPH
sensor
Oil separator
(G)
Solenoid valve
C : 3D052628
Refrigerant Circuit
SiUS181631EA