Control Specification (15/18/24 Class) SiUS04-90452 Function and Control4.3 Controls at Mode Changing / Start-up4.3.1 Preheating OperationOutline Operate the inverter in the open phase operation with the conditions including the preheatingcommand from the indoor, the outdoor air temperature and discharge pipe temperature.Detail Preheating ON Condition When outdoor air temperature and discharge pipe temperature are below 51ºF, inverter in openphase operation starts.OFF Condition When outdoor air temperature or discharge pipe temperature is higher than 54ºF, inverter inopen phase operation stops.4.3.2 Four-Way Valve SwitchingOutline During the heating operation the valve must be energized, and during cooling and defrosting,current must not be energized. In order to eliminate the switching sound (as the four-way valve coilswitches from ON to OFF) when the heating operation is stopped, the delay switch of the four-wayvalve must be carried out after the operation has stopped.Detail The OFF delay of four-way valveEnergize the coil for 150 seconds after unit operation is stopped.4.3.3 Four-Way Valve Operation CompensationOutline At the beginning of the operation as the four-way valve is switched, acquire the differential pressurerequired for activating the four-way valve by having output frequency, which is more than a certainfixed frequency, for a certain fixed time.Detail Starting Conditions1. When starting compressor for heating.2. When the operating mode changes from the previous time.3. When starting compressor for starting defrosting or resetting.4. When starting compressor for the first time after the reset with the power is ON.Set the lower limit frequency to 55 (model by model) Hz for 70 seconds with any conditions 1through 4 above.4.3.4 3-Minute StandbyProhibit to turn ON the compressor for 3 minutes after turning it off.(except when defrosting)4.3.5 Compressor Protection FunctionWhen turning the compressor from OFF to ON, the upper limit of frequency must be set as follows.(The function must not be used when defrosting.)FCG 1FCG 2FCG 3TCG1TCG2TCG3557085120200470(Hz)(R10540)Time (Sec)
