Fujitsu AUG12LVLB Service Instruction page 37

Trouble shooting 2
INDOOR UNIT Error Method:
Serial communication error
(Serial forward transfer error)
Detective Actuators:
Indoor unit Controller PCB
Forecast of Cause:
1. Connection failure
Check Point 1-1 : Reset the power and operate
Does error indication reappear?
YES YES
Check Point 2 : Check connection
Check any loose or removed connection line of
between indoor unit and outdoor unit.
>> If there is an abnormal condition, correct it by
referring to Installation Manual or Data &
Technical Manual.
Check connection condition in control unit.
(If there is loose connector, open cable or mis-wiring)
OK
Check Point 3 : Check the voltage of power supply
Check the voltage of power supply
>> Check if AC198V(AC220V-10%) - 264V(AC240V+10%) appears
at outdoor unit terminal L - N.
OK
Check Point 4 : Check serial signal (Forward transfer signal)
Check serial signal (Forward transfer signal)
>> Check if indicated value swings between AC70V and AC130V at outdoor unit terminal 2 - 3.
>> If it is abnormal, replace Controller PCB.
N
WHITE
BLACK L
RED 3
2
WHITE
1
BLACK
AMP Air Conditioning
Indicate or Display:
Refer to error code table.
Detective details:
When the outdoor unit cannot properly receive the serial signal from
indoor unit for 10 seconds or more.
2. External cause 3. Controller PCB failure
NO
+
-
Check Point 1-2 : Check external cause such as noise
Check if the ground connection is proper.
Check if there is any equipment that causes harmonic wave
near the power cable (Neon light bulb or any electronic
equipment which causes harmonic wave).
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02-04