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Viessmann · Heat pumps · Viessmann Vitocal 250-A (One Base, monobloc)

F.812Upper fan not running.

Name in the manufacturer's documentation (service manual): Upper fan not running.[1]

In plain words (editorial)

The upper fan of the outdoor unit is not running, so the refrigerant circuit will not start. The manual says to check that the fan can rotate freely, isolate the system from the power supply and restart it.

When to call a service technician: If the fault persists, contact your heating contractor.

✎ 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] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified F.812
  2. [2] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified Check connections on VCMU
  3. [3] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified Check fan can rotate freely
  4. [4] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified Check upper fan via actuator test
  5. [5] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified Isolate the system from the power supply
  6. [6] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified Restart the system
  7. [7] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified If the fault persists, replace the upper fan
  8. [8] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 61 manufacturer document – copy from a distributor quote verified The refrigerant circuit will not start