Service Manual
Table Of Contents
SiUS091601EA Troubleshooting for Outdoor Unit
Part 6 Service Diagnosis 180
7.16 Signal Transmission Error on Outdoor Unit PCB
Error Code U7
Method of Error
Detection
Communication error between microcomputer mounted on the main PCB and PM1.
Error Decision
Conditions
The abnormality is determined when the data sent from the PM1 cannot be received for 9
seconds.
The error counter is reset when the data from the PM1 can be successfully received.
Supposed
Causes
Defective outdoor unit PCB
Troubleshooting
(R21808)
Caution
YES
NO
Turn off the power. Then, turn on
the power to restart the system.
Error again?
The cause can be an
external factor other than
the malfunction.
Observe the operating
condition in long term.
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
Replace the outdoor unit
PCB (main PCB).