Troubleshooting Guide
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Only training and service purposes.
1. Power cable or communication cable is not
connected
2. Defect of outdoor Main PCB or Inv. PCB
Error
No.
Error Type
Error Point
Main Reasons
Main PCB of Master unit
of Master unit can’t
receive signal from Inv.
PCB
Communication error
between
(Inv. PCB
‘
Main PCB)
521
n
Error diagnosis and countermeasure flow chart
Is communication
LED (Yellow) of
Inv. PCB on?
No
Re-connect communication cable
Is communication cable
connected correctly?
Yes
No
Re-connect communication cable
Is Main PCB normal?
Yes
No
Replace Main PCB
Replace Inv. PCB
* The method of checking Main PCB and Inv. PCB (If normal, communication LED blinks)
Yes
No
Turn on the heat exchanger module.
Yes
Is the heat exchanger
module turned on?
Inverter Communication LED
Inverter Communication
Connector