SiUS281811EA Troubleshooting by Error Codes
Part 6 Service Diagnosis 279
4.49 Check Operation Not Executed
Error Code U3
Applicable
Models
All outdoor units
Method of Error
Detection
Determined based on whether check operation is executed or not
Error Decision
Conditions
Error is decided when the unit starts operation without check operation.
Supposed
Causes
Check operation not executed
Troubleshooting
Replace the outdoor main PCB (A1P).
Press TEST (BS4) button on
master outdoor unit PCB for 5
seconds or longer to check
operation.
Has the check
operation performed
on outdoor unit
PCB?
NO
YES
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
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