Hitachi FSG Series Service Manual page 63

Alarm Code
51
n "RUN" light flickers and "ALARM" is indicated on the remote control switch.
n The unit No., alarm code and the unit code is alternately indicated on the set temperature section, and the
unit No. and alarm code are indicated on the display of the outdoor unit PCB.
‘
This alarm code is indicated when the current transformer is abnormal (0A detection) and its state occurs
more than 3 times in 30 minutes.
Condition of Activation: When the frequency of compressor is maintained at 15~18Hz after compressor is
Restart operation.
How is compressor operation
when restarted?
*1): P17 is shown at 7-segment on the outdoor unit PCB.
*2): Perform the high voltage discharge work by referring to 1.3.6 before checking and replacing the inverter parts.
Abnormality of Current Transformer (0A Detection)
started, one of the absolute value of running current at each phase U+, U-, V+ and V-
is less than 0.5A (including 0.5A).
Compressor stops
immediately. (nearly 18Hz)
Compressor is not operated.
P17 is appeared. *1)
Yes
Is the coil resistance of comp.
normal?
Yes
Is output of transistor module
correct? *2)
Yes
Replace PCB3
TROUBLESHOOTING
Power wiring of Comp. is not
through CT.
Pass the wires through CT.
Faulty PCB3 and
Replace PCB3 *2)
No
Replace Comp.
No
Check transistor module.
1
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