F5
Day & Night
Indoor–Outdoor Capacity Mismatch / Configuration Error
F5 code, unit may short-cycle or fail to maintain setpoint
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect indoor or outdoor unit size configured on PCB, Wrong model configuration jumper, Mixed-match components not approved by Day & Night, Corrupted configuration data
How to Fix / Troubleshooting
Safety first: Disconnect power to both indoor and outdoor units before adjusting configuration.
- Step 1 – Verify model numbers: Check the nameplates on both indoor and outdoor units to ensure they are an approved matched system per Day & Night documentation.
- Step 2 – Check DIP switches/jumpers: On the indoor board, confirm tonnage and airflow settings match the installed equipment size. Adjust according to the wiring diagram.
- Step 3 – Outdoor configuration: Some communicating condensers require setting capacity or staging options via DIP switches. Verify these settings.
- Step 4 – Power cycle: After corrections, power cycle the system and monitor operation.
- Professional assistance: If F5 persists, a Day & Night dealer may need to reprogram or replace control boards to match the system configuration.
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Repair Difficulty
Hard
4/5
Required Part
Indoor Control Board Configuration
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