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9-2. Protective Functions
9-2-1. Operation Cut-off Control in Abnormal Ambient Temperature
The following three protective actions are available to prevent the compressor from operating with abnormal
loads. At that time, they initiate thermo-off (stopping the outdoor unit) of the air conditioner.
9-2-2. Operation Cut-off Control for Excessive / Low Voltage
If the voltage of the power supply is intolerably higher or lower than the rated voltage, power-off will trip (power
supply to the outdoor unit is stopped) to protect the unit, regardless of the operating mode. When this function is
activated, the speed of the indoor fan operates at LL speed and the operation lamp starts to flash.
9-2-3. Overload Prevention in Heating
This function reduces the load on the compressor by controlling the operating frequency before the protective cir-
cuit activates while operating in Heating mode.
(a) Area — the air conditioner follows auto performance
control.
(b) When the temperature rises above point A, the operat-
ing frequency is reduced at a specified rate.
(c) Area — further frequency rise is not allowed.
(d) When the temperature falls below point B, overload pre-
vention mode is released and the air conditioner oper-
ates as in (a).
9-2-4. Freeze Prevention
If the temperature of the indoor heat exchanger drops to the following level while the air conditioner is operating
in Cooling or Dry mode, it will detect a freeze condition and stop operation as long as necessary.
1. When the temperature of the indoor heat exchanger is less than 6°C, the air conditioner enters Freeze
Prevention mode.
2. Release of freeze prevention mode occurs when the temperature of the indoor heat exchanger is over 8°C.
(a) Area — the air conditioner follows auto performance
control.
(b) When the temperature falls below point A, the operating
frequency is reduced at a specified rate.
(c) Area — further frequency rise is not allowed.
(d) When the temperature rises above point C, freeze pre-
vention is released and the air conditioner operates as
in (a).
If the temperature falls below 2°C (for more than 2 minutes) the compressor will stop operating.
Once the freeze condition is detected, the air conditioner will work less than the maximum fre-
quency until it is turned off.
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