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Special Control
SiUS28-902_a
25
Function
3.4
Pump-down Residual Operation
When activating the compressor, if the liquid refrigerant remains in the heat-exchanger, the
liquid enters into the compressor and dilutes oil therein resulting in a decrease of lubricity.
Therefore, the pump-down residual operation is performed to collect the refrigerant in the heat-
exchanger when the compressor is down.
3.4.1 Pump-down Residual Operation in Cooling Operation
3.4.2 Pump-down Residual Operation in Heating Operation
Actuator
Master unit operation
Compressor
124 Hz
Outdoor unit fan
Fan control
Four-way valve
OFF
Main electronic expansion valve (EV1)
2000 pls
Subcooling electronic expansion valve (EV2)
0 pls
Hot gas bypass valve (SVP)
OFF
Receiver gas discharging valve (SVG)
ON
→
OFF
Ending conditions
•
30 sec.
•
Pe<73 psi
•
Td>230
°
F
or
Actuator
Master unit operation
Compressor
124 Hz
Outdoor unit fan
STEP 8
Four-way valve
ON
Main electronic expansion valve (EV1)
0 pls
Subcooling electronic expansion valve (EV2)
0 pls
Hot gas bypass valve (SVP)
OFF
Receiver gas discharging valve (SVG)
ON
→
OFF
Ending conditions
•
3 min.
•
Pe<36 psi
•
Td>230
°
F
or
Summary of Contents for SkyAir FCQ18PVJU
Page 1: ...Split System Air Conditioners SkyAir Inverter R 410A Heat Pump 60Hz P Series SiUS28 902_a...
Page 44: ...Other Control SiUS28 902_a 37 Function...
Page 81: ...SiUS28 902_a Troubleshooting by Remote Controller Troubleshooting 74...
Page 185: ...SiUS28 902 Precautions for New Refrigerant R 410A Precautions for New Refrigerant R 410A 178...