Daikin Altherma fault F3-00

What it means

Discharge pipe thermistor detects a too high temperature.

Likely causes

1. Closed stop valve in the refrigerant circuit
2. Refrigerant overcharge or shortage
3. Non-condensables and/or humidity in the refrigerant circuit
4. Clogged refrigerant circuit
5. Faulty 4-way valve
6. Faulty expansion valve control
7. Faulty main PCB
8. Faulty refrigerant side thermistor(s)
9. Faulty room thermistor
10. Deviation of thermistor (higher temperature measured than actual).
11. Bad contact between sensor and pipe
12. Deviation of outlet water after backup heater thermistor (lower temperature measured than actual)
13. Deviation of thermistor (lower temperature measured than actual)
14. Incorrect refrigerant charge
15. Faulty suction thermistor
16. Blockages in refrigerant circuit
17. Faulty discharge pipe thermistor
18. Domestic hot water tank thermistor measures a higher temperature than actual (component failure)

Where to start

1. Check that all stop valves of the refrigerant circuit are open (see 4.2 Refrigerant circuit)
2. Check if the refrigerant circuit is correctly charged (see 4.2 Refrigerant circuit)
3. Check for the presence of non-condensables and/or humidity in the refrigerant circuit (see 4.2 Refrigerant circuit)