Daikin Altherma fault E8-00

What it means

Compressor running current exceeds standard value for 2.5 seconds, indicating an overvoltage/overcurrent condition on the power input.

Likely causes

1. Outdoor temperature is out of operation range
2. Faulty compressor or miswiring of the compressor power supply cable
3. Faulty inverter PCB
4. Faulty or disturbance of the power supply (power supply MUST be within range of nominal operating voltage ±4%)
5. Power drop
6. Short circuit
7. Faulty refrigerant pressure sensor
8. Poor water flow through high pressure side plate heat exchanger
9. Incorrect refrigerant charge
10. Bad contact between refrigerant loop and inverter heat sink
11. Lack of refrigerant
12. Faulty expansion valve
13. Faulty suction thermistor
14. Blockages in refrigerant circuit
15. Faulty discharge pipe thermistor
16. Worn or damaged compressor dampers causing vibration/noise
17. Compressor guard timer active
18. Normal inverter control behavior when target temperature achieved
19. Water pump software control behaviour based on setting [F-0D]
20. Special software control activated - water loop temperature is too low causing ONLY the backup heater to operate
21. Faulty compressor winding
22. High pressure switch confirmed faulty during checking procedure
23. Flammable refrigerant remaining dissolved in compressor lubricant
24. Wrong assembly during repair
25. Excessive heat applied during brazing near compressor pipes

Where to start

1. Check the outdoor temperature
2. Perform a check of the compressor
3. Perform a check of the inverter PCB