LG ACHH Series Manual page 95

Error number Errors
Outdoor unit 4 way
151
valve switching
(11 → 511)
error
n How to diagnose the disorder
Is 4way valve
connector correctly
connected?
Yes
Is 4way valve coil
resistance value
normal? (Note 1)
Yes
Is 4way valve coil
correctly connected to the
wary valve? (Note 2)
Yes
Does master outdoor
unit recognize the slave
outdoor unit? (Note 3)
Yes
Is 220V measured at
PCB when heating starts
after reset? (Note 4)
Yes
Does compressor
properly operate?
Yes
After operating in the opposite
operation mode from the
current operation mode, does
the error occur again?
Yes
Replace 4way valve (Note 5)
Meaning
Outdoor unit 4 way valve
switching failed
No
Connect the connector again
No
Replace 4way valve coil
No
Connect the 4way valve coil again
No
Refer to error 51 and take action
No
Replace outdoor unit PCB
No Check and replace compressor,
magnet switch, and the corresponding
PCB (Electronic parts)
No
If the same error occurs again in the
future, replace 4way valve
Main cause of occurrence
1. 4way valve malfunction by entrance of foreign object
2. No high pressure/low pressure difference generated due
to damage of the compressor
3. Incorrect installation of the common pipe between outdoor
units
4. 4way valve unit defect
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Error code check