Daikin Altherma fault J6-07

What it means

Heat exchanger thermistor input is out of range, causing the unit to stop operating.

Likely causes

1. Faulty heat exchanger thermistor
2. Faulty main PCB
3. Deviation of thermistor (higher temperature measured than actual).
4. Faulty room thermistor
5. Bad contact between sensor and pipe
6. Deviation of outlet water after backup heater thermistor (lower temperature measured than actual)
7. Deviation of thermistor (lower temperature measured than actual)
8. Incorrect refrigerant charge
9. Faulty expansion valve control
10. Faulty suction thermistor
11. Blockages in refrigerant circuit
12. Faulty discharge pipe thermistor
13. Domestic hot water tank thermistor measures a higher temperature than actual (component failure)

Where to start

1. Perform a check of the heat exchanger thermistor
2. Perform a check of the main PCB
3. Check discharge pipe thermistor.