SiAU18-715 Special ControlFunction 873.4 Pump-down Residual OperationWhen activating compressor, if the liquid refrigerant remains in the heat-exchanger, the liquidenters 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 Operation3.4.2 Pump-down Residual Operation in Heating Operation3.5 Restart StandbyRestart is stood by force to prevent frequent power-on/off and to equalize pressure in therefrigerant system.Actuator Pump-down residual operation Step 1 Pump-down residual operation Step 2Compressor 124 Hz Full load 52 Hz Full loadOutdoor unit fan Fan control Fan controlFour way valve OFF OFFMain electronic expansion valve (EV1) 480 pls 240 plsSubcooling electronic expansion valve(EV3) 0 pls 0 plsHot gas bypass valve (SVP) OFF OFFEnding conditions 2 sec. 2 sec.Actuator Pump-down residual operationCompressor 124 Hz Full loadOutdoor unit fan STEP7Four way valve ONMain electronic expansion valve (EV1) 0 plsSubcooling electronic expansion valve(EV3) 0 plsHot gas bypass valve (SVP) OFFEnding conditions 4 sec.Actuator Operation RemarksCompressor OFF Outdoor unit fan Ta>30°C: STEP4Ta≤30°C: OFF Four way valve Keep former condition. Main electronic expansion valve (EV1) 0 pls Subcooling electronic expansion valve(EV3) 0 pls Hot gas bypass valve (SVP) OFF Ending conditions 2 min.
