Service Diagnosis
59
U4
Description
COMMUNICATION ABNORMALITY
Possible Root
cause
1. Faulty outdoor unit PCB.
2. Faulty indoor unit PCB.
3. Indoor unit – outdoor unit signal transmission error due to wiring error.
4. Indoor unit – outdoor unit signal transmission error due to disturbed power supply waveform.
5. Indoor unit – Outdoor unit signal transmission error due to breaking of wire in the connection
wires between the indoor and outdoor units
Troubleshooting
*Remark:
Refer to Appendix A for power supply waveform check procedures.(Page 73, item 6.9)
Is the
voltage fluctuation
within ±10% from the
rated value?
Yes
Yes
Rotate
the outdoor fan
by hand. Does the
outdoor fan rotate
smoothly?
Yes
Yes
Check the power supply voltage.
Check the indoor unit - outdoor
unit connection wires.
No
Check the LED A on the
outdoor unit PCB.
Check the power supply waveform.
Check the voltage of the
connection wires on the indoor
terminal board between No. 1(L) and
SIG, and between No. 2 (N)and SIG.
Replace the connection wires
between the indoor unit and
outdoor unit.
Locate the cause of the
disturbance of the power
supply waveform, and correct it.
No
Correct the indoor unit -
outdoor unit connection wires.
Diagnose the outdoor unit
PCB.
Replace the outdoor fan motor
and the outdoor unit PCB.
Is there any
wiring error?
Properly connected?
Is there any
disturbance?
Yes
Is LED A blinking?
Yes
No
No
Correct the power supply.
No
Replace the indoor unit PCB.
No
#Refer section 4.0 Wiring Connection Diagram