Si12-411A Troubleshooting
Service Diagnosis 179
5.8 Signal Transmission Error (between Indoor and Outdoor
Units)
Remote
Controller
Display
U4
Method of
Malfunction
Detection
The data received from the outdoor unit in indoor unit-outdoor unit signal transmission is
checked whether it is normal.
Malfunction
Decision
Conditions
When the data sent from the outdoor unit cannot be received normally, or when the content of
the data is abnormal.
Supposed
Causes
Faulty outdoor unit PCB.
Faulty indoor unit PCB.
Indoor unit-outdoor unit signal transmission error due to wiring error.
Indoor unit-outdoor unit signal transmission error due to disturbed power supply waveform.
Indoor unit-outdoor unit signal transmission error due to breaking of wire in the connection
wires between the indoor and outdoor units (wire No. 2).
Troubleshooting
Check No.10
Refer to P.212
Check the outdoor unit's LED A.
Check the indoor unit-outdoor unit
connection wires.
YES
YES
Correct the indoor unit-outdoor
unit connection wires.
Diagnose the outdoor unit.
Replace the connection wires
between the indoor and
outdoor units.
Replace indoor unit control
PCB .
Locate the cause of the
disturbance of the power supply
waveform, and correct it.
Is there any wiring error?
NO
(R2840)
Is LED A flashing?
Is the voltage 0 V?
NO
Check No. 10
Check power supply waveform.
Check the voltage of the indoor
unit-outdoor unit connection wires
between No. 1 and No. 2, and
between No 2 and No. 3.
YES
YES
NO
Is there any disturbance?
NO
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
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