Panasonic U-4..6ML5XPQ, Service Manual

Page: 69 / 283

Special Control
Function 57
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 Pump-down residual operation Step 1 Pump-down residual operation Step 2
Compressor 124 Hz Full load 52 Hz Full load
Outdoor unit fan Fan control Fan control
Four way valve OFF OFF
Main electronic expansion valve (EV1) 480 pls 240 pls
Subcooling electronic expansion valve
(EV3)
0 pls 0 pls
Hot gas bypass valve (SVP) OFF OFF
Ending conditions 2 sec. 2 sec.
Actuator Pump-down residual operation
Compressor 124 Hz Full load
Outdoor unit fan STEP7
Four way valve ON
Main electronic expansion valve (EV1) 0 pls
Subcooling electronic expansion valve
(EV3)
0 pls
Hot gas bypass valve (SVP) OFF
Ending conditions 4 sec.
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