Forced Cooling Operation; Fresh Air Control; External Electrical Heater Control; Compressor Preheating - Fujitsu AB A30LBT Series Service Instruction

1-17. FORCED COOLING OPERATION

The forced cooling operation starts up when MANUAL / AUTO button is pressed more than 10 seconds.
During the forced cooling operation, it keeps operation regardless of detection value of room
temperature sensor.
Operation LED and timer LED blink during the forced cooling operation. They blink for 1 second ON
and 1 second OFF on both operation LED and timer LED (same as test operation).
Forced cooling operation is released after 60 minutes of starting operation.

1-18. FRESH AIR CONTROL

The fan motor for Fresh Air is operated in synchronization with the indoor fan operation
as shown in Figure 9.
(Fig.9 : Fresh air control)
Operation
Fan motor
(Indoor unit)
Stop
Operation
Fan motor
(for Fresh Air)
Stop

1-19. EXTERNAL ELECTRICAL HEATER CONTROL

The external electrical heater is operated as shown in Figure 10.
(Fig.10 : External electrical heater control)
Ts -3°C
Ts -12°C
When the room
temperature drops

1-20. COMPRESSOR PREHEATING

When the outdoor heat exchanger temperature is lower than 0°C and the heating operation
has been stopped for 30 minutes, power is applied to the compressor and the compressor is heated.
(By heating the compressor, warm air is quickly discharged when operation is started.)
When operation was started, and when the outdoor temperature rises to 2°C or greater,
preheating is ended.
(Fig.11 : Compressor preheating control)
Tn 0°C
When the room
temperature rises
Heater : OFF
Heater : ON
Heater : OFF
OFF
ON
01-18
Ts : Setting temperature
Ts -1°C
When the compressor stop,
External electrical heater is OFF.
Ts -10°C
utdoor heat exchanger
Tn : O
temperature
Tn 2°C