Outdoor Unit Pcb Abnormality Or Communication Circuit Abnormality - Daikin CTXU25G2V1B Service Manual

Troubleshooting
2.33 Outdoor Unit PCB Abnormality or Communication
Circuit Abnormality
U4
Remote
Controller Display
Method of Detect within the program of the microcomputer that the program is in good running order.
Malfunction
Detection
Malfunction 1. When the program of the microcomputer is in bad running order.
2. When indoor-outdoor unit signal transmission can not be performed for more than 15
Decision
Conditions
3. When zero-cross signal can not be detected for more than 10 seconds.
Supposed
Causes
157
seconds.
Display disabled due to power supply fault
Communication circuit fault in outdoor unit PCB
Out of control of microcomputer caused by external factors
Noise
Momentary voltage drop
Momentary power loss
Defective outdoor unit PCB
Defective thermal fuse in outdoor terminal board
SiBE12-908
Service Diagnosis