DAMA-SM-21-001 Troubleshooting
Service Diagnosis 64
4.7 Low-voltage Detection or Over-voltage Detection
Error Code U2
Method of Error
Detection
Low-voltage detection:
An abnormal voltage drop is detected by the DC voltage detection circuit.
Over-voltage detection:
An abnormal voltage rise is detected by the DC over-voltage detection circuit.
Error Decision
Conditions
Low-voltage detection:
The voltage detected by the DC voltage detection circuit is below 180 - 196 V (depending on
the model).
The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
Over-voltage detection:
An over-voltage signal is fed from the over-voltage detection circuit to the microcomputer.
The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
Supposed
Causes
Troubleshooting
Power supply voltage out of specification
Defective DC voltage detection circuit
Defective over-voltage detection circuit
Defective PAM control part
Disconnection of compressor harness
Short circuit inside the fan motor winding
Noise
Momentary drop of voltage
Momentary power failure
Defective outdoor unit PCB
Correct the power supply.
Check for such factors for a
long term.
NO
NO
YES
YES
NO
YES
YES
Reconnect the harness.
Check the power supply voltage.
Check the connection of the
compressor harness.
Disturbance factors
* Noise
* Power supply distortion
(Precaution before turning on the power again)
Make sure the power has been off for at
least 30 seconds.
Replace the outdoor
unit PCB (main PCB).
Turn on
the power. System
restarted? (Repeat a few
times.)
Loose or
disconnected?
NO
Replace the outdoor fan motor
and the outdoor unit PCB
(main PCB).
Does the
outdoor fan rotate
smoothly?
Is the
voltage fluctuation
within ±10% from the
rated value?
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
Caution
To Next Page
Loading...
Need help?
General