E347
No 24V output on Y1 of integrated control with non-communicating outdoor unit
This code typically points to
- Y1 relay / stage-1 pilot relay contacts did not close
- Relay coil did not energize
- No input back to IFC chip
Next checks to confirm
- Verify stage-1 call is present
- Check Y1 output from integrated control
- If relay logic/output has failed, replace integrated control
Escalation
Critical alert; operation stopped
Reset behavior
Cleared after reset and Y1 input is sensed.
Urgent
Fix now