Outdoor Unit Pcb Abnormality Or Signal Transmission Error - Daikin 2MKS40G2V1B Service Manual

Troubleshooting for Outdoor Unit
7.17 Outdoor Unit PCB Abnormality or Signal Transmission
Error
U4
Remote
Controller
Display
Method of
Malfunction
Detection
Malfunction
Decision
Conditions
Supposed
Causes
257
Detection within the program of the microcomputer
Indoor-outdoor unit signal transmission performance
Presence or absence of zero-cross signal
The program of the microcomputer is in bad running order.
Indoor-outdoor unit signal transmission can not be performed for more than 15 seconds.
Zero-cross signal cannot be detected for more than 10 seconds.
Display disabled due to power supply fault
Communication circuit fault in outdoor unit PCB
Noise
Momentary fall of voltage
Momentary power failure
Defective outdoor unit PCB
Defective thermal fuse on outdoor terminal board
SiBE12-816_D
Service Diagnosis