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