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Flashes DEFROST (green)

LED: DEFROST (green) Flashes — Some protection is active

NIBE · S2125 Air/Water Heat Pump

What does Flashes DEFROST (green) mean?

The green DEFROST LED on the base board (AA2) is flashing, indicating that some protection function is currently active.

Common Causes

  • System is running a protective measure (e.g., against overheating, pressure issues).
  • Temporary condition.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Observe the system for any accompanying alarms on the indoor module/control module display.

  2. 2

    Allow the system to complete its protection cycle.

  3. 3

    If the flashing persists without other visible issues, consult the manual for the specific protection active or contact support.

Browse all codes in this manual (55)
Verified technical data. Last updated: April 2026

Related Faults

Communication fault to Inverter 254Alarm 254 (or 264, 203) Communication fault to Inverter — Inverter unpowered or brokenCompressor speed too low 354Alarm 354 (or 503, 186) Compressor speed too low — Inverter safety function reduces compressor speedContinuous light CPULED: CPU Continuous light — CPU is not running correctly
Source: NIBE S2125 Air/Water Heat Pump
Open Manual (Page 32)Search more codes in this manual