LG ARUV Series Service Manual page 254

Troubleshooting Guide
Error
Error Type
No.
21 IPM fault of inverter com-
pressor
Error diagnosis and countermeasure flow chart
Are the resistance between
each phase and insulation resistance
of Inverter compressor normal ?
[refer electric component part]
Yes
Is inverter PCB of inverter
compressor normal?
[refer electric component part]
Yes
Is IPM normal?
[refer electric component part]
Yes
Is capacitor normal?
[refer electric component part]
Yes
Is IPM SUB PCB
normal? *
Yes
Is compressor lead cable
connection normal?
[refer electric component part]
Yes
Does cooling fan
of heat sink rotate
normally?
Yes
Is magnetic switch
Normal?
Yes
Check main power and
installation condition
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Error Point
Defective inverter com-
pressor, Inverter element
(IPM) defect
No
Replace inverter compressor
No
Replace inverter compressor PCB
No
Replace IPM
No
Replace capacitor
No
Replace IPM SUB PCB
No
Check / repair the connection
No
Replace radiation cooling fan
No
Replace Magnetic switch
* Check the soldering state
of IPM SUB PCB
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Main Reasons
1. Over current detection at the inverter com-
pressor (U,V.W)
2. IPM overheating.
3. Insulation damage of the compressor /
compressor motor damage
4. Low input voltage at the outdoor
5. Inverter compressor terminal disconnected
or loose.
6. Inverter PCB / IPM PCB defect
LGE Internal Use Only