Daikin SKYAIR Service Manual page 27

Service Diagnosis
Description Communication Abnormality
Supposed 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
Troubleshooting
Check the power supply voltage.
Check the power supply waveform.
*Remark:
Refer to Appendix A for power supply waveform check procedures (Item 4, page 34).
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wires between the indoor and outdoor units.
Is the
voltage fluctuation
within ±10% from the
rated value?
Yes
Check the indoor unit - outdoor
unit connection wires.
Is there any
wiring error?
No
Check the voltage of the
connection wires on the indoor
terminal board between No. 1 and
SIG, and between No. 2 and SIG.
Properly insulated?
No
Check the LED A on the
outdoor unit PCB.
Is LED A blinking?
Yes
Rotate
the outdoor fan
by hand. Does the
outdoor fan rotate
smoothly?
Yes
Is there any
disturbance?
Yes
U4
No
Yes
Yes
No
No
No
Correct the power supply.
Correct the indoor unit -
outdoor unit connection wires.
Replace the connection wires
between the indoor unit and
outdoor unit.
Diagnose the outdoor unit
PCB.
Replace the outdoor fan motor
and the outdoor unit PCB.
Replace the indoor unit PCB.
Locate the cause of the
disturbance of the power
supply waveform, and correct it.