Panasonic

Minor / Info Important – service soon Critical – stop & diagnose

General meaning: Controller does not have a stored fault. Often shown when you enter self-diagnosis mode and no error is present.

Controllers: Same meaning across all Aquarea controllers (H, J/K/L, HT, T-CAP).

Checks:

  • If unit is not operating as expected, check scheduling & setpoints rather than faults.
  • Confirm all zone thermostats are calling for heat / DHW as expected.

Recommended action: None – this is effectively “no error”.

General meaning: Loss of communication between indoor/hydrobox and outdoor unit over the signal wiring.

H-series / older bi-bloc: Often described as “indoor–outdoor abnormal communication” (check S1/S2 link and control PCBs).

J/K/L, HT, T-CAP: Same meaning, sometimes with added note to check remote controller bus if multiple controllers are fitted.

Checks:

  • Power present at both indoor & outdoor units.
  • Signal cable correctly landed on S1/S2 (no mix with Live/Neutral).
  • Continuity test of signal cable; check for damage, joints, water ingress.
  • Correct polarity and single cable run (no star wiring).

Recommended action: Power-cycle the system. If H11 returns, isolate, verify wiring, then suspect indoor or outdoor PCB and involve an F-Gas engineer.

General meaning: Indoor and outdoor units are not a compatible capacity combination, or field settings do not match.

Controllers: Same core meaning across Aquarea; details vary by model (incorrect indoor/outdoor pairing or wrong PCB capacity settings).

Checks:

  • Confirm indoor and outdoor model numbers are a supported pairing.
  • Check that any replacement PCB has correct capacity setting adaptor / DIP switches.
  • Verify field settings for capacity / model (per service manual).

Recommended action: Installer / engineer task – do not ignore; system may not control pressures/loads correctly.

General meaning: Indoor intake air / room temperature sensor open- or short-circuit, or reading out of range.

Checks:

  • Check sensor plug is fully seated on PCB or controller.
  • Inspect cable for damage, pinched or extended wiring.
  • Measure thermistor resistance and compare to Panasonic curve.

Recommended action: Replace sensor if readings are out of spec or intermittent.

General meaning: Compressor discharge / shell temperature sensor fault (open/short or unrealistic reading).

Checks:

  • Sensor connection on outdoor PCB and at compressor body.
  • Thermistor resistance at various temperatures.
  • Signs of overheating or burn marks at terminals.

Recommended action: Engineer to test and replace sensor; investigate overheating causes if compressor is very hot.

General meaning: Abnormal current detected by outdoor inverter (IPM) / current transformer. Often linked to power electronics or compressor issues.

Recommended action: Treat as an engineer-only fault – check supply quality, IPM module, compressor windings and earth leakage.

General meaning: Faulty thermistor on refrigerant suction line to compressor (open/short / out of range).

Checks: As per other thermistor faults – connector, cable, resistance curve.

General meaning: In AC this is “indoor fan mechanism lock”. On Aquarea hydronic units it may indicate a circulation pump fault / lock depending on model.

Checks:

  • Fan coil units: check fan spins freely and is not blocked; test motor.
  • Hydrobox: check primary pump spins freely; free any stuck rotor and clean filter/strainer.

General meaning: The control does not see expected flow or pump feedback.

Checks (installer/engineer):

  • Confirm pump receives power when demanded.
  • Check pump speed setting and that isolation valves are open.
  • Bleed air and ensure system pressure is adequate.

General meaning: Indoor float switch operated or faulty – usually condensate or drip tray water level in AC, or tank/condensate in some hydronic units.

Checks: Check for water buildup, blocked drains, stuck float, or faulty switch.

Sensor on indoor coil / plate heat exchanger (open/short / out of range).

Second indoor coil / HEX sensor abnormal (where fitted).

Used mainly on indoor AC units that have ion or air-purification modules. Not normally present on pure hydronic Aquarea indoor units.

Outdoor ambient sensor faulty or disconnected.

Primary outdoor coil sensor fault.

Compressor discharge pipe thermistor fault.

Used when a dedicated pool temperature sensor is configured.

Second outdoor coil / HEX sensor abnormal (multi-sensor units).

Wrong combination of indoor/outdoor units, or incorrect piping/wiring layout.

Cooler / heat-sink temperature sensor fault on inverter module.

These codes are grouped around water-side reverse flow and gas-pipe sensor abnormalities.

  • H35 – Indoor/outdoor water adverse current (flow direction / valve issue).
  • H36 – Outdoor gas pipe temperature sensor abnormal.
  • H37 – Additional water pipe / flow-direction abnormality, model-specific.

“Abnormal water outlet sensor” – leaving-water thermistor error.

General meaning: Flow sensor / flow switch detects insufficient water flow in the primary circuit.

H-series installation manual: Often described as “Primary flow error – flow sensor detects a problem with the primary flow rate (usually too low)”.

Other Aquarea documentation: Often described as a “flow rate / flow switch error caused by lack of water flow between heat pump and house plumbing”.

Checks (installer/engineer):

  • Check system pressure and bleed air from all high points.
  • Clean Y-strainer and any filters/sludge traps.
  • Verify all valves are open and zone valves are actually opening.
  • Confirm pump speed and that required flow rate is achieved (per kW output).
  • If using LLH/buffer, confirm correct hydraulic separation and primary flow.

Recommended action: Restore correct flow, then reset error. Persistent H62 after good hydraulics suggests faulty flow sensor/switch or pump issue.

In many Aquarea hydronic manuals H70 is “Abnormal backup heater OLP” (overload protection) or a closely related backup-heater safety. In some installer literature it is grouped with flow / backup heater lockouts.

Checks: Backup heater wiring, contactors, over-temperature cutoff, and continuity of heater elements; verify correct water flow over heater.

“Abnormal tank sensor” – DHW cylinder temperature probe faulty or not connected.

“PCB communication error” – problem with internal communication between PCBs (e.g. main and expansion boards).

“Indoor–remote controller communication error” – problem on the wired controller bus or Smart Cloud link (depending on setup).

“Abnormal tank heater OLP” – over-temperature or overload protection for cylinder immersion heater has tripped.

“Abnormal voltage connection” – incorrect supply voltage, phase, or serious power issue.

Recommended action: Electrician/engineer to verify supply, phasing (3-phase), earthing, and terminal tightness before further operation.

General use: F11 appears both as a cooling/heating cycle changeover abnormality and as an indoor pipe temperature sensor fault in different manuals.

Some Aquarea hydronic units: “Indoor pipe temperature sensor abnormality” – treat as a thermistor fault on the indoor water heat exchanger.

Some multi / PACI systems: “Cooling / heating cycle changeover abnormality” – 4-way valve or control issue.

Checks:

  • Hydronic: check indoor HEX sensor wiring and resistance curve.
  • Refrigerant: check 4-way valve coil, wiring, and that valve shifts correctly.

F27 has sub-codes for open interconnect cables and incorrect data transfer between indoor and outdoor units.

Checks: As for H11, but also check power conductors and screen/earthing on multi-unit systems.

Outdoor non-volatile memory (EEPROM) read/write failure on main PCB.

  • F90: PFC (power-factor correction) control abnormal.
  • F91: Inverter / compressor drive error (model-specific wording).
  • F95: Outdoor high-pressure protection.
  • F96: IPM / power transistor overheating protection (sometimes paired with P07).
  • F97: Related inverter/power error, sometimes paired with P03 in Aquarea error histories.

Recommended action: All are engineer-level faults – check refrigerant charge, airflow, water flow, expansion valve, and inverter electronics.

In Aquarea service tables P03 and P07 are paired with F96/F97 as module-level inverter alerts (power transistor protection, module overheating, etc.).

“AC Power Supply Trouble” – serious issue with incoming electrical supply.

Checks: Supply voltage, phasing, loose neutrals, and terminal tightness.

Some hydronic/boiler-linked systems use these for “alarm valve open”, “O₂ sensor detect”, etc. On most domestic Aquarea heat pumps these will be rare or unused.

General meaning: Refrigerant shortage or blockage in the refrigeration circuit, commonly described as a “gas shortage” alert.

Checks (F-Gas engineer only): Leak testing, subcool/superheat analysis, check for closed valves or blocked strainers/driers, then recharge to spec.

On Aquarea-based water heat-exchanger and multi systems these “U-codes” are mostly power and system-layout related: low/high supply voltage, incorrect wiring, too many indoor units, etc.

They are far less common on simple domestic Aquarea splits/monoblocs but may appear if integrated with other Panasonic systems.

Recommended action: Treat as design/supply/layout issues – check wiring diagrams, supply quality and system addressing.