Daikin VRV S RXQ4/5ARV1 Service Manual page 65

SiAF332111E
1.2.3 Electronic Expansion Valve PI Control
Injection Electronic Expansion Valve Control
Performs PI control of the electronic expansion valve Y2E (RXMQ10/12ARY1) to keep the
superheating degree (SH) of the outlet gas pipe on the evaporator side for full use of the
subcooling heat exchanger.
SH = Tsh – Te
1.2.4 Cooling Operation Fan Control
In cooling operation with low outdoor air temperature, this control is used to provide an
adequate amount of circulation air with liquid pressure secured by high pressure control from
the outdoor fan.
Furthermore, when outdoor temperature  20°C, the compressor will run in Step 7 or higher.
When outdoor temperature  18°C, the compressor will run in Step 5 or higher.
When outdoor temperature  12°C, the compressor will run in Step 1 or higher.
Fan Steps
Part 4 Functions and Control
Pc < 2.75 MPa (4/5 HP)
Pc < 3.23 MPa (10/12 HP)
PI control
A lapse of 20 seconds
–1 step on
outdoor fan
PI control
Fan speed (rpm)
Step 4/5 HP
M1F
0 0
1 200
2 250
3 300
4 360
5 430
6 515
7 620
8 830
SH: Evaporator outlet superheating degree (°C)
Tsh: Subcooling heat exchanger gas pipe temperature
detected with the thermistor R6T (°C)
Te: Low pressure equivalent saturation temperature (°C)
Upper limit of fan
revolutions: Step 8
Pc > 3.24 MPa (4/5 HP)
Pc > 3.45 MPa (10/12 HP)
Upper limit of outdoor fan
revolutions
Step 7
PI control
Hold the
current step on
outdoor fan
A lapse of 20 seconds
10/12 HP
M1F M2F
0 0
300 0
450 0
335 300
430 395
515 480
620 585
760/890 725/890
970 970
Control for 4/5/10/12 HP Outdoor Unit
Pc: High pressure sensor detection value
+1 step on
outdoor fan
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