A6
Nibe Compressor overload / motor protection trip

A6 alarm, compressor locked out, unit may run only on electric backup

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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

Locked or seized compressor, incorrect supply voltage, faulty compressor contactor, failing start components (for single‑phase models)

How to Fix / Troubleshooting

Safety: High voltages and stored energy are present. Do not attempt to open compressor terminals.

  • Check supply voltage and fuses: Verify that all phases (for 3‑phase Nibe units) are present and that no fuses or breakers have tripped. An electrician should correct any supply issues.
  • Inspect contactor: With power off, inspect the compressor contactor for burnt contacts or loose wiring. Replace only if you are qualified; otherwise call a technician.
  • Reset alarm: After ensuring stable power, reset the A6 alarm via the control panel. If the alarm returns immediately when the compressor tries to start, stop the unit.

A recurring A6 alarm usually requires a Nibe service technician to test compressor windings, motor protection, and start components, and to replace the compressor if seized.

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Repair Difficulty

Professional Required 5/5

Required Part

Compressor Overload Protector
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