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Fronius · PV inverters · Fronius Symo 3.0–20.0 (three-phase grid inverter, SnapINverter)

STATE 304AC module overtemperature

Name in the manufacturer's documentation (service manual): AC module overtemperature[1]

In plain words (editorial)

The AC module of the inverter is too hot. Feeding into the grid is interrupted briefly and the inverter restarts its start-up routine. The manual says to clean (purge) the cooling air openings and heat sink; the fault clears automatically.

When to call a service technician: If the code keeps recurring, contact your system installer.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 016-24082016) – distributor copy (42,0410,2028 (016-24082016)) , p. 46 manufacturer document – copy from a distributor quote verified 304 AC module overtemperature
  2. [2] Fronius Symo / Fronius Eco – Operating Instructions (e-Manual HTML), Version 044-17072025 – chapter “Status diagnostics and troubleshooting” (text capture) (e-Manual 4204101909, 044-17072025) , p. 3 official manufacturer document quote verified Purge cooling air openings and heat sink
  3. [3] Fronius Symo / Fronius Eco – Operating Instructions (e-Manual HTML), Version 044-17072025 – chapter “Status diagnostics and troubleshooting” (text capture) (e-Manual 4204101909, 044-17072025) , p. 3 official manufacturer document quote verified Fault is rectified automatically. If this status code keeps recurring, contact your system engineer
  4. [4] Fronius Symo / Fronius Eco – Operating Instructions (e-Manual HTML), Version 044-17072025 – chapter “Status diagnostics and troubleshooting” (text capture) (e-Manual 4204101909, 044-17072025) , p. 3 official manufacturer document quote verified Short-term interruption while feeding energy into the grid. The inverter resumes with its startup routine.