SiUS121502E Control SpecificationFunction and Control 653.4 Controls at Mode Changing / Start-up3.4.1 Preheating ControlOutline The inverter operation in open phase starts with the conditions of the outdoor temperature and thepreheating command from the indoor unit.Detail ON Condition When the outdoor temperature is below 20°C (68°F), the inverter operation in open phasestarts.OFF Condition When the outdoor temperature is higher than 22°C (71.6°F), the inverter operation in openphase stops.3.4.2 Four Way Valve SwitchingOutline The four way valve coil is energized / not energized depending on the operation. (Heating: ON,Cooling / Dry / Defrost: OFF) In order to eliminate the switching sound as the four way valve coilswitches from ON to OFF when the heating is stopped, the OFF delay switch of the four way valveis carried out.Detail OFF delay switch of four way valve:The four way valve coil is energized for 150 seconds after the operation is stopped.3.4.3 Four Way Valve Operation CompensationOutline At the beginning of the operation as the four way valve is switched, the pressure difference toactivate the four way valve is acquired when the output frequency is higher than a certain fixedfrequency, for a certain fixed time.Detail Starting Conditions1. When the compressor starts and the four way valve switches from OFF to ON2. When the four way valve switches from ON to OFF during operation3. When the compressor starts after resetting4. When the compressor starts after the fault of four way valve switchingThe lower limit of frequency keeps A Hz for 70 seconds with any conditions 1 through 4 above.3.4.4 3-Minute StandbyTurning on the compressor is prohibited for 3 minutes after turning off.(The function is not used when defrosting.)A (Hz) Cooling Heating18 class 74 6224/36 class 42 35
