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Possible causes
I/U - O/U communication error
(detected by I/U)
AImproper connector connection between I/U and O/U
BImproper wire connection between I/U and O/U
CFailure of I/U or O/U board
DCase thermo sensor ON
EInvalid I/U board switch setting
[E04]
(New code)
C
B
A
Does O/U work?
Is group address set correctly?
Are 1/2/3 wires normal?
Are connectors from I/U and
O/U connected normally?
Is I/U switch SW02
setting correct? Bit 1, 2: OFF
Does voltage between
I/U terminal 2 and 3 fluctuate?
(0-140 VDC)
Is 280VDC
applied across IPDU main
circuit capacitor?
Is 280VDC supplied to
CDB? (CN03)
Is 7VDC supplied
to CDB? Is CN06-CN800
connection normal?
Is case thermo sensor
connected? (CN500)
Is case thermo sensor working?
Check and correct refrigerant volume.
Check I/U boards.
® Replace defective board.
Check code “14”.
Correct wires.
Correct connector connection.
Correct switch setting on
MCC-1510 board.
Check MCC-1510 board.
→ Replace it if necessary.
Black
White
Terminal block
Replace IPDU.
Check MCC-1510 board.
→ Replace it if necessary.
Check CDB. → Replace it if
necessary.
Correct connector connection.
Replace IPDU.
Correct connector connection.
Replace IPDU.
NO NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
* Measure within
20 seconds
from power on.
Troubleshooting (Continued)
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