Mini UM S/M
Special Control
Function
41
3.4
Pump-down Residual Operation
When activating compressor, if the liquid refrigerant remains in the heat-exchanger, the liquid
enters into the compressor and dilutes oil therein resulting in 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<0.5 MPa
•
Td>110
°
C
or
Actuator
Master unit operation
Compressor
124 Hz
Outdoor unit fan
STEP8
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<0.25 MPa
•
Td>110
°
C
or
Mini UM.book Page 41 Monday, January 24, 2005 11:32 AM
