Function Details Si-71A66 Explanation of Function Operation5.2.3 HPS/LPS Detection FunctionIf either HPS or LPS are actuated while the compressor is running, the compressor stops and beginsstanding by for 3 minutes. (Depending on operation conditions, even if LPS is actuated the compressormay not go OFF in some cases)If this movement is detected an additional 5 times from the time it is first detected to until turned off byremote controller, operation is stopped due to malfunction.5.2.4 Electronic Expansion Valve ControlElectronicExpansionValve InitializeAbout 10 seconds after turning on the power supply, the electronic expansion valve’s opening is tightened520 pulses to close it all the way.Discharge PipeTemperatureThe optimal discharge pipe temperature for present operation is calculated according to indoor unit heatexchange temperature, outdoor unit heat exchange temperature, and outdoor air temperature, with theelectronic expansion valve being controlled so that the discharge pipe temperature approaches the optimaldischarge pipe temperature.Optimal discharge pipe temperature - discharge pipe temperature <0°C (superheat operation)→ Motor operated valve is openedOptimal discharge pipe temperature - discharge pipe temperature >0°C (wet operation)→ Motor operated valve is closed.5.2.5 Abnormally High Discharge Pipe TemperatureIf discharge pipe high temperature thermostat OFF or T2 (discharge pipe thermistor) disconnection isdetermined 6 times or wet operation protection control is determined, operation stops due to abnormaldischarge pipe temperature.Wet OperationProtection ControlCooling : Discharge pipe temperature < outdoor unit heat exchanger temperature +10°C15 minutes in successionHeating : Discharge pipe temperature < indoor unit heat exchanger temperature +10°C15 minutes in successionand the electronic expansion valve openning is 50 pulses or less.5.2.6 Discharge Pipe High Temperature Thermostat OFF ControlIf discharge pipe temperature T2 remains above 123.5°C for 100 seconds in succession, or above 140°Cfor 20 seconds in succession, the thermostat is turned OFF.5.2.7 T2 Disconnection Thermostat OFF ControlIf the discharge pipe thermistor is determined to be disconnected from the piping 5 minutes after thecompressor starts, the thermostat is turned OFF.5.2.8 Lack of Gas MalfunctionWhen the thermostat is turned OFF due to abnormally high discharge pipe temperature, lack of gasmalfunction occurs if the opening of the solenoid valve is 450 pulses or more. Operation however does notstop due to lack of gas. Lack of gas malfunction can be checked by remote controller inspection.5.2.9 Emergency OperationÑ No signal is transmitted between the indoor and outdoor units.Ñ Emergency operation is not possible if the motorized valve has a malfunction.Ñ Switches on the control printed circuit boards of both indoor and outdoor units are used for anemergency operation.The outdoor unit’s control printed circuit board is used for the changeover of the cooling/heating mode.Ñ In heating operation, defrosting operation is activated once every hour.
