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CONTROL
3. How the system operates during defrost control
The system operates as follows during defrost control.
(1) Apparent engine speed is controlled by normal control in heating operation.
(2) Sub heat exchanger liquid flow control valve is set to standard upper limit open position, and normal
control in heating operates after that.
(3) The open position of the outdoor heat exchanger liquid flow control valve is fixed at 0.
(4) The open position of the subcooling valve is fixed at 0.
(5) The open position of the oil bypass control valve is subject to normal control in heating operation.
(6) Outdoor fan air volume level is fixed at 0.
(7) Reversing valve is fixed OFF.
(8) Hot gas bypass valve is fixed OFF.
4. Judgment of the end of defrosting
1) Return to normal heating operation
The system returns to normal heating operation when any of the following conditions is met.
2) Stop of defrost control
Defrost control stops and normal stop process operates when any of the following conditions is met.
7) Outdoor Fan
1. Control in cooling operation
The following control operates to maintain refrigerant high pressure (refrigerant high-low pressure difference)
and engine coolant (or engine oil) temperature, and to avoid abnormal engine coolant temperature.
Condition to increase fan air volume
Fan air volume is increased by 1 level when any of the following conditions is met.
Condition to decrease fan air volume
Fan air volume is decreased by 1 level when any of the following conditions is met.
2. Control in heating operation
The following control operates to maintain evaporating capacity and engine coolant (or engine oil) tempera-
ture, and to avoid abnormal engine coolant temperature.
Condition to increase fan air volume
Specified time has passed from starting of defrost control. OR
High pressure equivalent temperature is higher than the specified value. OR
Outdoor heat exchanger liquid temperature is higher than the specified value.
When all the indoor units stops temperature control operation. OR
Any abnormality that requires the outdoor unit to stop running occurs.
The refrigerant high pressure is the specified value or higher. OR
The engine coolant temperature is the specified value or higher.
The refrigerant high pressure is lower than the specified value. OR
The engine coolant temperature is lower than the specified value.
The engine coolant temperature is the specified value or higher. OR
Apparent engine speed is the specified value or more and the difference between outside air temper-
ature and low pressure equivalent temperature is the specified value or higher.
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