SiUS181631EA Special ControlFunctions and Control 573.2 Oil Return OperationIn order to prevent the compressor from running out of oil, the oil return operation is conducted torecover oil flown out from the compressor to the system side.3.2.1 Oil Return Operation in Cooling OperationConditions to startOil return operation in cooling operation is started referring to the following conditions: Cumulative oil feed rate Timer setting (Make this setting so as to start the oil return operation when the initial cumulativeoperating time reaches 2 hours after power supply is turned ON and then every 8 hours.)The cumulative oil feed rate is computed from Tc, Te, and compressor loads.Outdoor unit actuator Oil return preparationoperation Oil return operation Post-oil-return operationCompressor Take the current step as theupper limit. 52 Hz Full load (→ Lowpressure constant control) Same as in oil returnoperation mode.Outdoor fan Fan control (Normal cooling) Fan control (Normal cooling) Fan control (Normal cooling)Four way valve (Y1S) OFF OFF OFFMain electronic expansion valve (Y1E) 480 pulse 480 pulse 480 pulseSubcooling electronic expansion valve(Y3E) SH control 0 pulse 0 pulseHot gas bypass solenoid valve (Y2S) OFF OFF OFFEnding conditions 20 sec.• 3 min.• Ts1 – Te < 5°C(9°F)• 3 min.• Pe < 0.6 MPa(201 ftAq)• HTdi > 110°C(230°F)or orIndoor unit actuator Cooling oil return operationIndoor fanThermostat ON unit Remote controller settingStopping unit OFFThermostat OFF unit Remote controller settingElectronic expansion valve ofBP unitThermostat ON unit SH controlStopping unit 77 pulseThermostat OFF unit SH control
