Daikin Altherma fault H3-00
Outdoor unit: malfunction of high pressure switch
Heat pumpWhat it means
High pressure switch is activated when compressor is off.
Likely causes
- High pressure switch confirmed faulty during checking procedure
- Faulty refrigerant pressure sensor
- Poor water flow through high pressure side plate heat exchanger
- Incorrect refrigerant charge
Where to start
- Perform a check of the high pressure switch
- Check refrigerant pressure sensor
- Check high pressure side plate type heat exchanger for good water flow and heat exchange
The full answer, free
- 10 more checks in order
- The readings and component tests from the manual
- How to put it right, step by step
- The manual page for this fault (page 46), right under the answer
Safety: Isolate the outdoor unit and any backup heater, and give the inverter capacitors time to discharge before you open the electrics. Anything on the refrigerant circuit needs F-gas certification.
From the Daikin manual for the Altherma. Check the model on the data plate before you order parts.
Other Daikin Altherma fault codes
- 4-02Incorrect setting of space heating OFF temperature
- 7HFlow error (minimum flow rate not reached)
- 7H-01Water flow problem
- 7H-04Water flow problem during domestic hot water production
- 7H-05Water flow problem during heating/sampling
- 7H-06Water flow during cooling/defrost
- 7H-07Water flow problem. pump de-blocking active
- 7H-XXWater flow or volume too low
- 80-00Inlet water thermistor abnormality
- 81-00Outlet water thermistor abnormality
- 81-01Mixed water thermistor abnormality
- 89-01Heat exchanger frozen
- 89-02Heat exchanger frozen
- 89-03Heat exchanger frozen
- 8F-00Abnormal increase outlet water temperature (domestic hot water)
- 8H-00Abnormal increase outlet water temperature
- 8H-01Overheating mixed water circuit
- 8H-02Overheating mixed water circuit (thermostat)
- 8H-03Safety thermostat circuit open with jumper removed
- A1-00Zero cross detection problem
- A5-00Outdoor unit: high pressure peak cut / freeze protection problem
- AA-01Backup heater overheated
- AA-02External backup heater overheated
- AC-00Booster heater overheated