LG ACHH Series Manual page 96

Error code check
4way valve connector location in main PCB
(Note 1) Measure resistance to see
if 4way valve is normal (It is marked as CN16_VI, CN25_BK)
*Normal value: several kΩ
(Note 2) Check if the coil is fully inserted in 4way valve.
(Note 3) During the heating operation, check if 220V is output from PCB
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