Viessmann · Heat pumps · Viessmann Vitocal 250-A (One Base, monobloc)
A.86Faulty signal, flow temperature sensor, secondary circuit or heating/cooling circuit 1
Name in the manufacturer's documentation (service manual): Faulty signal, flow temperature sensor, secondary circuit or heating/cooling circuit 1
[1]
This page only quotes the original English documentation. A plain-language explanation has not been written yet, so the page is not indexed by search engines.
For technicians
Steps given by the manufacturer (source text)
- Check resistance value (NTC 10 kΩ) at connection X4.1/X4.2 of the EHCU electronics module. Replace sensor if necessary[2]
What the device does (source text)
- No room heating, heating/cooling circuit 1[3]
⚠ Work on refrigerant circuits, mains electricity and PV DC wiring is for qualified technicians only.
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] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 70 manufacturer document – copy from a distributor quote verified
A.86
- [2] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 70 manufacturer document – copy from a distributor quote verified
tion x4.1/x4.2 of the ehcu elec-
- [3] Viessmann – Service instructions: System configuration and diagnosis for heat pumps with Viessmann One Base (6194799 GB, 3/2022) (6194799 GB (3/2022)) , p. 70 manufacturer document – copy from a distributor quote verified
no room heating, heating/