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Troubleshooting
2.17 Signal Transmission Error (between Indoor Unit and
Outdoor Unit)
U4
Error Code
Method of Error
The data sent from the outdoor unit is checked for problem.
Detection
Error Decision
The data sent from the outdoor unit cannot be received without error, or the disable status of
signal transmission continues for 15 seconds.
Conditions
Supposed
Causes
Troubleshooting
100
Wiring error
Breakage of relay wire (transmission wire)
Defective outdoor unit PCB
Defective fan motor
Defective indoor unit PCB
Be sure to turn off the power switch before connecting or disconnecting
Caution
connectors, or parts may be damaged.
Check the relay wire between the
indoor unit and the outdoor unit
for color and number.
Any improper wiring?
NO
Are the relay
wires and the earth
properly insulated?
OK
Does the distance of
relay wire exceed
30 m?
NO
Does LED A on the
outdoor unit blink?
YES
Rotate the
outdoor fan by hand.
Does the outdoor fan rotate
smoothly?
YES
Disconnect No. 3.
Measure the voltage between
No. 2 and 3 (Apply negative
terminal to No. 2 in DC range)
Is the measured
value 30 to 50 V?
NO
(below 30 V or above 50 V)
YES
Poor insulation
YES
NO
NO
YES
SiBE04-624_B
Correct the relay wire
between the indoor unit and
the outdoor unit.
Replace the relay wire
between the indoor and the
outdoor unit.
Distance is to be within the
specified range (30 m or
less).
Replace the outdoor unit
PCB.
Replace both the fan motor
and the outdoor unit PCB.
Voltage
7 sec.
15 sec.
Stop
Power on
Check during
Fault
this period
determined
Replace the indoor unit
PCB (Control PCB).
Replace the outdoor unit
PCB.
(R18125)
Service Diagnosis
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