Troubleshooting
SIE-86
66
Service Diagnosis
5.10
Signal Transmission Error (Between Indoor and Outdoor Units)
(U4)
Remote Controller
Display
UUU
U4444
Indoor unit LED
Display
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.13
Refer to P.82
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 PCBs (1).
Locate the cause of the
disturbance of the power supply
waveform, and correct it.
Is there any wiring error?
NO
(MF007)
Is LED A flashing?
Is the voltage 0 V?
NO
Check No. 13
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
Si-86.book Page 66 Friday, June 23, 2000 10:26 AM