“C4, 81, 80, Hc” Thermistor Or Related Abnormality (Hydro-Box) - Daikin Altherma EKHBH Series Service Manual

Error Codes: Hydro-box
"C4, 81, 80, HC" Thermistor or Related Abnormality (Hydro-box)
2.4
1
Error code
Method of
malfunction
detection
Malfunction
decision conditions
3 3
Supposed causes
4
Troubleshooting
5
3–10
C4, 81, 80, HC
The temperatures detected by the thermistors are used to determine thermistor errors.
When the thermistor input is more than 4.96 V or less than 0.04 V during compressor operation*.
* (reference)
When above about 212°C (less than 120 ohms) or below about –50°C (more than 1,860 kohms).
Note: The values vary slightly in some models.
Faulty connector connection
Faulty thermistor
Faulty PCB
Check the connector connection.
Is it normal?
YES
Check No. 06
Thermistor resistance check
Is it normal?
YES
C4:
Hydro-box heat exchanger thermistor
81:
Outlet water temperature thermistor
80:
Inlet water temperature thermistor
HC:
Sanitary water temperature thermistor
See also "Check No.06" on page 3-53.
NO
NO
ESIE06-03
Correct the connection.
Replace the thermistor.
(Replace the hydro-box PCB.)
Replace the hydro-box PCB.
Part 3 – Troubleshooting