Pump-Down Residual Operation - Panasonic Mini UM S Service Manual

Mini UM S/M
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
Actuator
Compressor
Outdoor unit fan
Four way valve
Main electronic expansion valve (EV1)
Subcooling electronic expansion valve
(EV2)
Hot gas bypass valve (SVP)
Receiver gas discharging valve (SVG)
Ending conditions
3.4.2 Pump-down Residual Operation in Heating Operation
Actuator
Compressor
Outdoor unit fan
Four way valve
Main electronic expansion valve (EV1)
Subcooling electronic expansion valve
(EV2)
Hot gas bypass valve (SVP)
Receiver gas discharging valve (SVG)
Ending conditions
Function
Master unit operation
124 Hz
Fan control
OFF
2000 pls
0 pls
OFF
ON → OFF
• 30 sec.
• Pe<0.5 MPa
or
• Td>110°C
Master unit operation
124 Hz
STEP8
ON
0 pls
0 pls
OFF
ON → OFF
• 3 min.
• Pe<0.25 MPa
or
• Td>110°C
Special Control
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