“U0” Insufficient Gas - Daikin Altherma EKHBH Series Service Manual

Error Codes: System Malfunctions
"U0" Insufficient Gas
4.2
1
Error code
Method of
malfunction
detection
3 3
Malfunction
decision conditions
4
5
Supposed causes
3–42
U0
Gas shortage detection I:
A gas shortage is detected by checking the CT-detected input current value and the compressor
running frequency.
Gas shortage detection II:
A gas shortage is detected by checking the difference between hydro-box heat exchanger temperature
and room temperature as well as the difference between outdoor unit heat exchanger temperature and
room temperature.
Gas shortage detection I :
DC current ≤
(A/Hz) × Output frequency +
However, when the status of running frequency > 55 (Hz) is kept on for a certain time.
Note: The values are different from model to model.
27 / 1000
71 class
Gas shortage detection II :
If a gas shortage error takes place 4 times successively, the system will be shut down. The error
counter will reset itself if this or any other error does not occur during the following 60-minute
compressor running time (total time).
Refrigerant shortage (refrigerant leakage)
Poor compression performance of compressor
Discharge pipe thermistor disconnected, or hydro-box or outdoor unit heat exchanger thermistor
disconnected, room or outside air temperature thermistor disconnected
Stop valve closed
Electronic expansion valve defective
2.5
ESIE06-03
Part 3 – Troubleshooting