L2
York
Loss of Communication with Outdoor Unit
York communicating thermostat shows L2 and outdoor unit does not respond
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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
Open or shorted communication bus, Incorrect wiring between thermostat, indoor, and outdoor, Faulty outdoor control board, Power loss to outdoor unit
How to Fix / Troubleshooting
Safety: Turn off all related breakers before working on wiring.
- Verify outdoor power: Confirm the York outdoor unit has correct line voltage and that its disconnect is on.
- Inspect communication wiring: On communicating systems, check the ABC or data terminals from thermostat to indoor and indoor to outdoor. Ensure polarity and color coding are consistent end‑to‑end.
- Check for shorts: Look for bare wires touching metal or each other. Repair or replace damaged cable.
- Reseat connectors: At the outdoor control board, remove and reinstall the communication plug to ensure good contact.
- If L2 persists: The outdoor control board or thermostat may be defective and should be tested by a York‑trained technician.
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Repair Difficulty
Hard
4/5
Required Part
Outdoor Control Board
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