SiAF332111E Control for 4/5/10/12 HP Outdoor Unit
Part 4 Functions and Control 59
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.
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
SH = Tsh – Te SH:
Tsh:
Te:
Evaporator outlet superheating degree (°C)
Subcooling heat exchanger gas pipe temperature
detected with the thermistor R6T (°C)
Low pressure equivalent saturation temperature (°C)
Step
Fan speed (rpm)
4/5 HP 10/12 HP
M1F M1F M2F
00 0 0
1 200 300 0
2 250 450 0
3 300 335 300
4 360 430 395
5 430 515 480
6 515 620 585
7 620 760/890 725/890
8 830 970 970
Upper limit of fan
revolutions: Step 8
Upper limit of outdoor fan
revolutions
Step 7
–1 step on
outdoor fan
+1 step on
outdoor fan
Pc
<
2.75 MPa (4/5 HP)
Pc
<
3.23 MPa (10/12 HP)
PI control
Pc
>
3.24 MPa (4/5 HP)
Pc
>
3.45 MPa (10/12 HP)
A lapse of 20 seconds
PI control
PI control
A lapse of 20 seconds
Hold the
current step on
outdoor fan
Pc: High pressure sensor detection value
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