F55 on a Panasonic heat pump: Not verified (M-series code; the list around F53-F56 reads "Main expansion valve overcurrent protection", "Bypass expansion valve overcurrent protection", "Electrical anode error" but one explanation could not be aligned)
Short answer
On a Panasonic heat pump, F55 means: Not verified (M-series code; the list around F53-F56 reads "Main expansion valve overcurrent protection", "Bypass expansion valve overcurrent protection", "Electrical anode error" but one explanation could not be aligned). The manual does not say whether the heat pump stops. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Not verified (M-series code; the list around F53-F56 reads "Main expansion valve overcurrent protection", "Bypass expansion valve overcurrent protection", "Electrical anode error" but one explanation could not be aligned).
Part involved: Unknown (M series).
When it shows: Not stated in the documents opened.
Likely causes:
- Not stated in the documents opened.
Is it safe?
| Does the heat pump stop? | Not stated |
|---|---|
| Engineer needed? | Yes |
The manual does not say whether the heat pump stops.
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
- Refer to the Aquarea M series service manual (PCZ2411004CE) for this code.
Who to ask for: Heat pump installer / commissioning engineer.
Certification: None statutory.
Sources
- Manuals+ rendering of Panasonic Operating Instructions WH-WXG09/12/16ME8 + WH-ADC0316M9E8(AN) (WEB-ACXF55-39380-EN) ↗ · WEB-ACXF55-39380-EN · page 54-55 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026