LG THERMA V AHBW076A0, Service Manual, Page: 59 / 98

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05
53
Bad communication
between main PCB
assembly(Inverter)
and main PCB as-
sembly(Heater)
• The connector for transmission is dis-
connected
• The connecting wires are miscon-
nected
• The communication line is broken
• main PCB(Heater) is abnormal
• main PCB(Inverter) is abnormal
• Wire connection between control panel
and main PCB 2 should be tight
Code
No.
Description Cause Normal Condition
Is main PCB(Heater)
LED blinking?
Yes
Yes
No
Is main circuit breaker off?
No
Check the main power
supply at the unit
terminal block?
Improper connection of power supply cable
Main power supply problem
Yes
No
Yes
No
main PCB(Inverter) fault
Replace after checking
Re-connect transmission cable
No
Yes
main PCB(Heater) fault
Replace after checking
Check the insulation of inverter
Check the capacity of main circuit
breaker and replace if required
If all ok,
Turn on main circuit breaker
Replace main PCB(Inverter) after
checking
Replace TRANS after checking
Check if the
transmission cable is
properly connected to
terminal block of
main PCB(Heater) and
main PCB(Inverter)
Control panel
displays CH05?
Replace main main PCB(Inverter)
Reconnect transmission cable
between main main PCB(Inverter)
and control panel
n
Error diagnosis and countermeasure flow chart