Refrigerant Circuit; Outdoor Unit - Daikin ALTHERMA HT ERSQ 011 AA Service Manual

Refrigerant Circuit

1. Refrigerant Circuit

1.1

Outdoor Unit

ERRQ - ERSQ
No. in
refrigerant
Symbol
system
diagram
A M1C Inverter compressor (INV)
M1F
B Inverter fan
M2F
Electronic expansion valve
C Y1E
(Main: EV1)
Electronic expansion valve
D Y3E
(Subcool: EV3)
E Y2S Solenoid valve (Hot gas: SVP)
Solenoid valve (Unload circuit
F Y3S
SVUL)
G Y1S Four way valve
H S1NPH High pressure sensor
I S1NPL Low pressure sensor
HP pressure switch (For INV
J S1PH
compressor)
Pressure regulating valve 1
K —
(Receiver to discharge pipe)
1 R1T Thermistor (Outdoor air: Ta)
Thermistor (INV discharge pipe:
2 R2T
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 pipe1: Tl1)
Thermistor
8 R8T
(Liquid pipe2: Tl2)
12
Name
Inverter compressor is operated on frequencies between 36 Hz and 195 Hz by using the
inverter. In total there are 31 steps.
Since the system is of air heat exchanging type, the fan is operated at 8 (9)-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 prevent the low pressure from transient falling.
Used to the unloading operation of compressor.
Used to switch the operation mode between defrosting and heating. Activated during heating
(opposite concerning indoor unit).
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.
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 superheat and internal temperature of compressor etc.
Used to control of subcooling electronic expansion valve.
Liquid thermistor (internal control), and others.
Liquid thermistor (internal control), and others.
Major Function
ESIE09-08A
Refrigerant Circuit