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304

Fronius Symo Hybrid Inverter Code 304 — AC module overtemperature

Fronius · Solar Inverters

What does 304 mean?

The AC module of the inverter has detected an excessively high temperature. This causes a short-term interruption in feeding energy, and the inverter will attempt to restart.

Common Causes

  • Blocked cooling air openings
  • Accumulation of dust or debris on heat sink
  • High ambient temperature
  • Inverter location with insufficient ventilation

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Purge the cooling air openings of the inverter to remove any blockages.

  2. 2

    Clean the heat sink to ensure proper heat dissipation.

  3. 3

    If this status code keeps recurring, contact your system fitter to check ventilation and inverter placement.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

1Error 1 (Binary 0001) — Hardware fault10Error 10 (Binary 1010) — General fieldbus error102Fronius Symo Hybrid Inverter Code 102 — AC voltage too high
Source: Fronius Solar Inverters
Open Manual (Page 124)Search more codes in this manual