Heat pumps · Error codes · Hisense
F1Hisense · Hi-Therma Monobloc (R32)
F1 on a Hisense Hi-Therma Monobloc: Alarm sent by Outdoor unit (Outdoor unit alarm 21-29)
Short answer
On a Hisense heat pump, F1 means: Alarm sent by Outdoor unit (Outdoor unit alarm 21-29). 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: Alarm sent by Outdoor unit (Outdoor unit alarm 21-29).
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: unknown.
What you can check
- Note the code shown on the controller and the unit model numbers (on the rating plate label) before contacting your installer.
- Check the heat pump's breaker/isolator at the consumer unit is on; do not open any casing.
What the engineer will check
- Read the outdoor unit 7-segment display for the originating alarm code and follow its flowchart.
Who to ask for: Heat pump engineer.
Certification: Heat pump installer competence; F-gas / flammable-refrigerant (R290/R32) handling competence for any refrigerant-circuit work.
What you might notice
Sources
- Air-to-Water Heat Pump Technical, Installation and Service Handbook - Hi-Therma Series (TCY12021017E) ↗ · TCY12021017E · page p.334 (printed; ManualsLib viewer p.355) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026