“U2” Low-Voltage Detection Or Over-Voltage Detection; Supposed Causes - Daikin Altherma EKHBH Series Service Manual

Error Codes: System Malfunctions
"U2" Low-voltage Detection or Over-voltage Detection
4.3
1
Error code
Method of
malfunction
detection
Malfunction
decision conditions
3 3

Supposed causes

4
Troubleshooting
5
Caution
3–44
U2
An abnormal voltage rise or drop is detected by checking the detection circuit or DC voltage detection
circuit.
An over-voltage signal is fed from the over-voltage detection circuit to the microcomputer, or the
voltage being detected by the DC voltage detection circuit is judged to be below 150 V for 0.1
second.
The system will be shut down if the error occurs 16 times.
Clearing condition: Continuous run for about 60 minutes (normal)
Supply voltage not as specified
Over-voltage detector or DC voltage detection circuit defective
PAM control part(s) defective
Check the supply voltage.
Supply voltage as
specified?
YES
Turn
on the power again.
System restarted?
NO
Repeat a
couple of times.
Be sure to turn off power switch before connect or disconnect connector, or parts damage may be
occurred.
NO
(Precaution before turning on the power again)
Make sure the power has been off for at least
30 seconds.
YES
Disturbance factors
∗ Noise ∗ Power supply distortion
ESIE06-03
Correct the power supply.
Check for such factors for a
long term.
∗ Try to get restarted a
couple of times.
Replace the PM1.
(Replace the outdoor unit
PCB.)
Part 3 – Troubleshooting