Refrigerant Circuit Part; Refrigerant Circuit; Rxtq36Tavju - Daikin VRV IV-S RXTQ-TAVJU Series Service Manual

Refrigerant Circuit

1. Refrigerant Circuit
1.1

RXTQ36TAVJU

No. in
piping Symbol
diagram
(1) M1C Inverter compressor
(2) M1F Inverter fan
Electronic expansion valve
(3) Y1E
(Main)
(4) Y1S Four way valve
(5) Y2S Solenoid valve (Hot gas)
(6) Y3S Solenoid valve (Unload circuit) Used for unloading operation of compressor.
(7) S1NPH High pressure sensor
(8) S1NPL Low pressure sensor
(9) S1PH High pressure switch
(10) — Fusible plug
Pressure regulating valve
(11) —
(Receiver to discharge pipe)
(12) R1T Thermistor (Outdoor air)
(13) R2T Thermistor (Discharge pipe)
(14) R3T Thermistor (Suction pipe 1)
Thermistor (Heat exchanger
(15) R4T
deicer)
(16) R5T Thermistor (Suction pipe 2)
(17) R7T Thermistor (Liquid pipe)
(18) R10T Thermistor (Radiation fin)
7
Name
Inverter compressor is operated on frequencies between 36 Hz and 195 Hz by using the
inverter.
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.
Used to switch the operation mode between cooling and heating.
Used to prevent the low pressure from transient falling.
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 (580 psi) 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 ~ 75°C (158 ~ 167°F) to
release the pressure into the atmosphere.
This valve opens at a pressure of 4.0 MPa (580 psi) or more 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 air 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 defrost operation,
and others.
Used for calculation of internal temperature of compressor etc.
Used to detect refrigerant overcharge in check operation, and others.
• Used for outdoor unit fan speed control.
• Used for inverter radiation fin temperature control.
• Used for pressure difference control.
Function
SiUS331604E
Refrigerant Circuit