F25 on a Panasonic heat pump: Cooling/Heating cycle changeover abnormality
Short answer
On a Panasonic heat pump, F25 means: Cooling/Heating cycle changeover abnormality. 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: Cooling/Heating cycle changeover abnormality.
Part involved: 4-way valve and V-coil.
When it shows: 1 During heating operation, when the indoor pipe temperature of thermostat ON indoor unit < 0°C. 2 During cooling operation, when the indoor pipe temperature of thermostat ON indoor unit > 45°C. Service-manual table judgement: 4 times occurrence within 30 minutes (L, K, J MDC, J MXC, J AIO, H, F, E, D5, D8, C).
Likely causes:
- 1 Faulty sensor. 2 Faulty connector connection. 3 Faulty outdoor unit PCB (noise filter/main). 4 Faulty four way valve.
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: Not stated in the Panasonic documents opened; protection counters lock out after the stated number of occurrences.
Manual reset: User: 'Error Reset' in the remote-controller Quick Menu (H/J/K/L controllers) or OFF/ON; engineer must clear the underlying cause (service manuals: 'When error happens, the power has to be reset').
What you can check
- Read and note the code shown blinking on the remote controller (also stored under System Check > Error history). Per the Panasonic operating instructions the user may switch the system OFF/ON at the remote controller and use 'Error Reset' in the Quick Menu; if the code returns, leave the system and contact the installer (UK user guide lists Panasonic technical support as the fallback).
What the engineer will check
- Check 4-way valve coil and operation; check indoor pipe/refrigerant sensor; check connectors and outdoor PCB.
Who to ask for: F-gas certified refrigeration / heat pump engineer (Panasonic-trained).
Certification: UK F-gas certification (Category I) for any refrigerant-circuit work; flammable-refrigerant competence for R32 (J/K) and R290 (L/M) units.
What you might notice
Sources
- Service Manual Hydromodule WH-SDC0509L3E5/L6E5 with WH-WDG05LE5/07LE5/09LE5 (Order No PAPAMY2307068CE) ↗ · PAPAMY2307068CE · page 190 (error codes table); 228 (self-diagnosis) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026