E5
York
Communication Error Between Indoor and Outdoor PCB
York split AC shows E5 and outdoor unit does not start
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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 cable, Reversed polarity or incorrect wiring, Faulty indoor control board, Faulty outdoor control board
How to Fix / Troubleshooting
Safety: Turn off all power to both indoor and outdoor units before working on wiring.
- Inspect communication cable: Trace the low‑voltage or data cable between the York indoor unit and outdoor unit. Look for cuts, rodent damage, or loose terminals. Tighten all screws and repair damaged cable.
- Verify wiring order: Compare the terminal labels (e.g., 1‑2‑3, S1‑S2‑S3, or R‑C‑Y) on both ends to the York wiring diagram. Correct any mis‑wired conductors.
- Check polarity and grounding: Ensure line and neutral are not reversed and that the system is properly grounded. Incorrect polarity can cause communication faults.
- Power reset: Turn off both breakers for 5 minutes, then restore power to the outdoor unit first, then the indoor unit, to allow proper boot sequence.
- If E5 returns: Either the indoor PCB or outdoor inverter/control board may be defective. A technician should perform board‑level diagnostics and replace the faulty board.
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Repair Difficulty
Hard
4/5
Required Part
Communication Cable
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