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SiUS121827E Control Specification
Part 4 Functions and Control 107
4.4 Controls at Mode Changing/Start-up
4.4.1 Preheating Control
Outline The inverter operation in open phase starts with the conditions of the outdoor temperature and the
preheating command from the indoor unit.
Details ON Condition
When the outdoor temperature is below 6°C (42.8°F), the inverter operation in open phase
starts.
OFF Condition
When the outdoor temperature is higher than 7.5°C (45.5°F), the inverter operation in open
phase stops.
4.4.2 Four Way Valve Switching
Outline The four way valve coil is energized/not energized depending on the operation mode (Heating: ON,
Cooling/Dry/Defrost: OFF). In order to eliminate the switching sound as the four way valve coil
switches from ON to OFF when the heating is stopped, the OFF delay switch of the four way valve
is carried out.
Details OFF delay switch of four way valve
The four way valve coil is energized for 150 seconds after the operation is stopped.
4.4.3 Four Way Valve Operation Compensation
Outline At the beginning of operation as the four way valve is switched, the pressure difference to activate
the four way valve is acquired when the output frequency is higher than a certain fixed frequency,
for a certain fixed time.
Details Starting Conditions
The compressor starts and the four way valve switches from OFF to ON
The four way valve switches from ON to OFF during operation
The compressor starts after resetting
The compressor starts after the fault of four way valve switching
The lower limit of frequency keeps A Hz for 70 seconds for any of the conditions above.
4.4.4 3-Minute Standby
Turning on the compressor is prohibited for 3 minutes after turning off.
(The function is not used when defrosting.)
Cooling Heating
A (Hz) 32 26
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