F3-24 on a Daikin heat pump: Compressor shell temperature error
Short answer
On a Daikin heat pump, F3-24 means: Compressor shell temperature error. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the Altherma 3 H HT (R-32 high temperature split)
The manual says: Compressor shell temperature error.
Part involved: refrigerant circuit / pressure protection.
When it shows: Compressor shell thermistor temperature <Tc (saturated condensation temperature) – 1 K for 30 minutes after compressor start‑up. EPRA14~18D + ETSH/X(B)16P30+50E Daikin Altherma 3 H HT ECH₂O 3 | Troubleshooting.
Likely causes:
- Faulty compressor shell thermistor or connector fault.
On the Altherma 4 H (R-290)
The manual says: OU: Malfunction of discharge pipe temperature.
Part involved: refrigerant circuit / pressure protection.
When it shows: Loosehanging compressor shell thermistor.
Is it safe?
On the Altherma 3 H HT (R-32 high temperature split)
| 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.
Manual reset: Manual reset via user interface.
On the Altherma 4 H (R-290)
| 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.
Manual reset: Manual.
What you can check
- Read the full error code and sub-code shown on the user interface (Malfunctioning screen; press the help button for Daikin's long description) and note it, with the date/time, for your installer.
- Look at the outdoor unit from outside: check the air inlet/outlet and fan grille are not blocked by leaves, debris, snow or heavy ice build-up (do not remove panels or touch the fan).
- Do NOT bleed radiators while an error/malfunction symbol is displayed: Daikin operation manuals warn refrigerant may have leaked into the water circuit - ventilate and call your installer.
- If heating/hot water has stopped, the operation manual lets the user confirm on the Malfunctioning screen whether the backup/booster heater may take over as emergency heating (much higher running cost) until the installer attends.
What the engineer will check
On the Altherma 3 H HT (R-32 high temperature split)
- Perform a check of the compressor shell thermistor.
Who to ask for: F-gas certified heat pump engineer (Daikin-trained installer / Stand By Me partner).
Certification: UK F-gas certification (Category I) for refrigerant circuit work; R-290 (Altherma 4) also needs flammable-refrigerant/hydrocarbon competence.
On the Altherma 4 H (R-290)
- See Daikin service manual for this generation (not public).
Who to ask for: F-gas certified heat pump engineer (Daikin-trained installer / Stand By Me partner).
Certification: UK F-gas certification (Category I) for refrigerant circuit work; R-290 (Altherma 4) also needs flammable-refrigerant/hydrocarbon competence.
What you might notice
What owners and engineers report
2 owner and engineer reports mention this.
- No heating on the Altherma 3 H HT (R-32 high temperature split): 1 report
- No hot water on the Altherma 3 H HT (R-32 high temperature split): 1 report
Sources
- Service manual Daikin Altherma 3 H HT ECH2O EPRA14-18D + ETSH/ETSX(B)16P30/50E (ESIE22-11A) ↗ · ESIE22-11A · page 55 · Reviewed 23 September 2026
- Installer reference guide Daikin Altherma 4 H W EPSK/EPSKS + EPBX(U) (4P773390-1C) ↗ · 4P773390-1C · page 212 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026