SiMT041311E
Troubleshooting
Service Diagnosis
176
2.37 Signal Transmission Error on Microcomputer for
Humidifying
Error Code
U7
Method of Error
Detection
Communication error between microcomputers mounted on the outdoor unit PCB.
Error Decision
Conditions
The data sent from the microcomputer for humidifying can not be received for 10 seconds.
Zero-cross signal on the microcomputer for humidifying cannot be detected.
Error counter is reset when the data from the microcomputer for humidifying can be
successfully received.
Supposed
Causes
Defective outdoor unit PCB
Noise
Troubleshooting
(R19732)
Caution
YES
NO
YES
NO
Turn off the power and turn it on
again
.
Check the varistor (V3, V5) on the
outdoor unit PCB.
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.
Is it broken?
Replace the outdoor unit
PCB.
Replace the varistor.