Outdoor Unit Pcb Abnormality Or Communication Circuit Abnormality - Daikin FTXZ25NV1B Service Manual

Troubleshooting
2.36 Outdoor Unit PCB Abnormality or Communication
Circuit Abnormality
U4
Error Code
Method of Error Detection within the programme of the microcomputer
Detection
Error Decision
Conditions
Supposed
Causes
173
The programme of the microcomputer does not work in order.
Indoor-outdoor unit signal transmission cannot be performed for more than 15 seconds.
Power supply voltage is not as specified.
Improper earth work
Defective varistor or fuse on the outdoor unit PCB
Defective thermal fuse on the terminal board of the outdoor unit
Disconnection of connecting wires
Defective outdoor unit PCB
Noise
Disturbed power supply waveform
Wrong wiring
Improper insulation of the connecting wires and earth
Defective indoor unit PCB
SiMT041311E
Service Diagnosis