
Troubleshooting Guide
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Copyright ©2013 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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1. CT sensor defect
2. Capacity over of AVR
3. Bridge R-N or S-N or T-N phase
voltage unequally at indoor unit
etc.
Error No.
Error Type
Error Point
Main Reasons
During operation (compressor fre-
quency is over 50Hz), difference
between R & T phase is 5A for 10
seconds.
Power Unbalance
74*
■
Error Diagnosis and Countermeasure Flow Chart
Recheck power and
installing condition
Yes
Is inverter PCB assembly
power wiring normal?
Check abnormal wiring between Inverter PCB assembly & bridge diode
(misconnection,disconnection)
→
Rewiring if abnormal wiring found
No
Yes
Is input voltage normal?
Check
R~S/S~T/T~R phase voltage is 380V 10%
R~N/S~N/T~N phase voltage is 220V 10%
→
Check connection condition and wiring if power is abnormal
No
Yes
Does indoor unit power
bridge R,S,T phase equally?
Bridge R-N,S-N,T-N voltage equally
No
Yes
Is inverter PCB
assembly normal?
Replace inverter PCB assembly
No
Measuring input voltage
Inverter PCB & Bridge Diode wiring
Summary of Contents for ARWN038GA2
Page 81: ...P NO MFL67101202 APRIL 2013 ...