Pump-Down Residual Operation Control - Daikin VRV - WII Service Manual

SiUS30-604
7.3

Pump-down Residual Operation Control

If any liquid refrigerant remains in the heat exchanger during compressor startup, the liquid
refrigerant will enter the compressor, resulting in the dilution of the refrigerating machine oil in the
compressor and the degradation of lubricating capacity.
Therefore, before the compressor stops, pump-down operation is performed to collect the
refrigerant in the heat exchanger.
7.3.1 Cooling Operation Mode
Parts name
Compressor
Inverter cooling fan
4 way valve (Main)
4 way valve
(for heat exchanger)
Main heat exchanger
electronic exp. valve
Sub-cooling electronic
exp. valve
Hot gas bypass solenoid
valve
Water heat exch. oil return
solenoid valve
Receiver gas charging
solenoid valve
Receiver gas discharge
solenoid valve
Non-operation unit liquid
pipe stop solenoid valve
Indoor cooling unit fan
Indoor cooling unit
expansion valve
BS 20RH
BS 20RT
Ending condition
Function
Electrical
Symbol
symbol
— (M1C)
— (M1, 2F)
20S1 (Y5S)
20S2 (Y7S)
EV1 (Y1E)
EV3 (Y3E)
SVP (Y1S)
SVE (Y2S)
SVL (Y3S)
SVG (Y4S)
SVSL (Y6S)
— (M1, 2F)
EV (Y1E)
20RH (Y3S)
20RT (Y1S)
Master unit operation
Current step
Inverter cooling fan control
OFF
OFF
2000 pulse
0 pls
ON
OFF
OFF
OFF
OFF
No instruction
All 0 pulse
BS unit control
BS unit control
Slave unit operation
OFF
Inverter cooling fan control
OFF
OFF
0 pulse
0 pulse
OFF
OFF
OFF
OFF
ON
Max. 5 min.
Special Operation
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