Heat pumps · Error codes · Technibel S.A.S.
CnTechnibel S.A.S. · Technibel PHRIE / PHIE inverter monobloc air-to-water (medium temperature)
Cn on a Technibel S.A.S. Technibel PHRIE / PHIE inverter monobloc air-to-water: System communication failure between A1 and A2 boards
Short answer
On a Technibel S.A.S. heat pump, Cn means: System communication failure between A1 and A2 boards. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: System communication failure between A1 and A2 boards.
Likely causes:
- Communication line fault.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: Automatic recovery; power-off reset recommended.
What you can check
- Note the code/LED pattern and the model from the rating plate, then contact a heat pump/refrigeration engineer.
- Check the heat pump's breaker/isolator at the consumer unit is on.
What the engineer will check
- Check wiring/connections.
- Check LED SC on A2 / C on A1.
- Check parameters.
- Check A2 and A1 boards.
Who to ask for: refrigeration / heat pump engineer.
Certification: Electrical competence for work inside the unit.
What you might notice
Sources
- Technibel PHRIE / PHIE inverter monoblock air to water heat pump, medium temperature, R410A - Service Manual (Jun. 2015, 10 12 211 - GB - 06) ↗ · 10 12 211 - GB - 06 · page 118 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026