F.817 on a Glow-worm GeniaAir: The inverter reports a fault in the compressor motor
Short answer
On a Glow-worm heat pump, F.817 means: The inverter reports a fault in the compressor motor. 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: The inverter reports a fault in the compressor motor.
Part involved: The inverter reports a fault in the compressor motor.
Likely causes:
- Defect in the compressor (e.g. short circuit). Defect in the frequency converter. Connection cable to the compressor is defective or loose.
- Glow-worm trade page: Frequency convertor (invertor PCB) fault – Compressor fault Fault in the wiring harness or connector to the compressor, fault in the invertor PCB, compressor fault.
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: no - the fault remains displayed until the cause is eliminated.
Manual reset: yes - after the cause is eliminated, press the reset button (indoor unit) or reset via the system control; if it recurs after several resets contact customer service.
What you can check
- Note the full code and text shown on the display (and the date/time it appeared). Check the heat pump supply breaker/isolator (and back-up heater breaker, if separate) at the consumer unit is on; if a breaker has tripped more than once, leave it off and call an engineer - do not open any casing. Glow-worm's MiPro Sense operating instructions say always contact your competent person in the event of a fault message; until they arrive you may select a limp-home (back-up heater) setting on the control, which is expensive to run.
What the engineer will check
- Measure the winding resistance in the compressor. 2. Disconnect the compressor for measurement and measure the frequency converter output between the three phases (it must be > 1 kΩ). 3. Check the wiring harness and plug connections.
Who to ask for: Heat pump engineer with electrical competence (qualified electrician for supply/phase faults).
Certification: Competent electrician (BS 7671 / Part P) for supply-side work.
What you might notice
Sources
- GeniaAir Appliance Interface installation and maintenance instructions ↗ · 8000043014_01 · page HPIM 7 8000043014_01 p.33 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026