F.823 on a Glow-worm GeniaAir: Compressor temperature switch has triggered
Short answer
On a Glow-worm heat pump, F.823 means: Compressor temperature switch has triggered. 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: Compressor temperature switch has triggered.
Part involved: Compressor temperature switch has triggered.
Likely causes:
- The hot gas thermostat shuts down the heat pump if the temperature in the refrigerant circuit is too high. Following a waiting period, the heat pump attempts to start once more. After three failed start attempts in succession, a fault message is displayed. Max. refrigerant circuit temperature: 130 °C. Waiting period: 5 mins (after it first occurs). Waiting period: 30 mins (after it occurs a second time and any other time after that). The fault counter is reset if both of the following conditions are met: Heat demand without switching off prematurely. 60 mins uninterrupted operation.
- Glow-worm trade page: Compressor temperature switch has triggered Electronic expansion valve (EEV) fault, fault in the electrical connection to the EEV, contamination in the refrigerant circuit i.e. dirt or moisture.
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 outdoor unit's air inlet and outlet are not blocked by leaves, debris, snow or ice build-up and clear any loose debris from around it (do not open the casing, poke the fins or use tools). 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. If you smell gas/solvent near the outdoor unit or hear hissing, switch the heat pump off at the isolator, keep ignition sources away and call an engineer.
What the engineer will check
- Check the EEV. 2. Replace the dirt filter in the refrigerant circuit, if required.
Who to ask for: F-gas certified refrigeration engineer with heat pump experience (R290 flammable-refrigerant competence required for aroTHERM plus / GeniaAir).
Certification: F-gas Category I (Regulation (EU) 517/2014 as retained in GB) certificate; flammable (R290) refrigerant training for R290 units.
What you might notice
Sources
- GeniaAir Appliance Interface installation and maintenance instructions ↗ · 8000043014_01 · page HPIM 7 8000043014_01 p.34 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026