Daikin Aurora Series, Service Manual, Page: 24 / 333

Refrigerant Circuit SiUS341802E
11 Refrigerant Circuit
1. Refrigerant Circuit
1.1 Outdoor Unit
No. in
piping
diagram
Electric
symbol
Name Function
(1) M1C Inverter compressor
Inverter compressor is operated on frequencies between 15 rps to 140 rps by using the
inverter. Refer to page 50, 51.
(2)
M1F
M2F
Inverter fan
Because the system is an air heat exchange type, the fan is operated at 53 steps of
rotation speed by using the inverter. Refer to page 53.
(3) Y1E
Electronic expansion valve
(Heat exchanger upper) While in heating, PI control is applied to keep the outlet superheated degree of air heat
exchanger constant.
(4) Y2E
Electronic expansion valve
(Subcooling heat exchanger) PI control is applied to keep the outlet superheated degree of subcooling heat exchanger
constant.
(5) Y3E
Electronic expansion valve
(Heat exchanger lower) While in heating, PI control is applied to keep the outlet superheated degree of air heat
exchanger constant.
(6) Y4E
Electronic expansion valve
(Subcooling injection)
Used to control compressor injection.
(7) Y5E
Electronic expansion valve
(Refrigerant cooling) Used to control the refrigerant amount to cool the diode bridge and power module of the
inverter PCB.
(8) Y6E
Electronic expansion valve
(Leak detection)
Used to detect refrigerant leakage.
(9) Y7E
Electronic expansion valve
(Receiver gas purge)
Used to collect the refrigerant to receiver.
(10) Y1S
Solenoid valve (Oil separator
oil return)
Used to return oil from the oil separator to the compressor.
(11) Y2S
Solenoid valve
(Hot gas bypass)
Used to flow discharge gas to the compressor inlet.
(12) Y3S Solenoid valve (Liquid shutoff) Used to shut off liquid refrigerant flow to the receiver.
(13) Y4S
Four way valve (HP/LP gas
pipe)
Used to switch dual pressure gas pipe to high pressure or low pressure.
(14) Y5S
Four way valve
(Heat exchanger lower)
Used to switch outdoor unit heat exchanger to evaporator or condenser.
(15) Y6S
Four way valve
(Heat exchanger upper)
(16) Y7S
Solenoid valve
(Accumulator oil return)
Used to return oil from the accumulator to the compressor.
(17) S1NPH High pressure sensor Used to detect the high pressure.
(18) S1NPL Low pressure sensor Used to detect the low pressure.
(19) S1PH
High pressure switch
(For inverter compressor) This functions when pressure increases to stop operation and avoid high pressure
increase in the fault operation.
(20) —
Pressure regulating valve
(Liquid pipe) This is used when pressure increases, to prevent any damage on components caused by
pressure increase in transport or storage.
(21) — Subcooling heat exchanger Apply subcooling to liquid refrigerant.
(22) — Capillary tube
Used to return the refrigerating oil separated through the oil separator to the inverter
compressor.
(23) R1T Thermistor (Outdoor air) Used to detect outdoor air temperature, correct discharge pipe temperature and others.
(24) R21T Thermistor (M1C discharge) Used to detect discharge pipe temperature.
(25) R3T Thermistor (Receiver inlet) Used to detect liquid pipe temperature of receiver inlet.
(26) R4T
Thermistor (Heat exchanger
liquid upper)
This detects temperature of liquid pipe for air heat exchanger.
(27) R5T
Thermistor (Heat exchanger
liquid lower)
(28) R6T Thermistor (Subcooling gas) This detects temperature of gas pipe for subcooling heat exchanger.
(29) R7T Thermistor (Subcooling liquid) This detects temperature of liquid pipe for subcooling heat exchanger.
(30) R8T
Thermistor (Heat exchanger
gas upper)
This detects temperature of gas pipe for air heat exchanger.
(31) R9T
Thermistor (Heat exchanger
gas lower)
(32) R10T Thermistor (Suction) Used to detect suction pipe temperature.
(33) R11T Thermistor (Deicer)
Used to detect liquid pipe temperature of air heat exchanger. Used to make judgements
on defrost operation.
(34) R12T
Thermistor (Compressor
suction)
Used to detect suction pipe temperature of compressor.
(35) R13T
Thermistor
(Receiver gas purge)
Used to detect gas pipe temperature of receiver gas purge piping.
(36) R14T Thermistor (M1C body)
Detects compressor surface temperature, this switch is activated at surface temperature
of 120°C (248°F) or more to stop the compressor.
(37) R15T Thermistor (Leak detection) The thermistor detects refrigerant leakage.
(38) R16T
Thermistor
(Subcooling injection)
Used to control subcooling injection.