Trouble shooting 2 INDOOR UNIT Error Method:
Indoor unit PCB model information error
Indicate or Display:
Refer to error code table.
Detective Actuators:
Indoor unit Controller PCB
Detective details:
When power is on and there is some below case.
1.When model information of EEPROM is incorrect.
2.When the access to EEPROM failed.
Forecast of Cause:
1. External cause 2. Defective connection of electric components 3. Controller PCB failure
Check Point
Does Error indication show again?
YES
Check Point 2 :
Check Indoor unit electric components
Check all connectors.
(loose connector or incorrect wiring) 
Check any shortage or corrosion on PCB.
NO
Check Point 1-2 :
Check external cause such as noise
Check if the ground connection is proper.
Check if there is any equipment that causes harmonic wave near the power cable (Neon light bulb or any electronic equipment which causes harmonic wave).
Check Point 3 : Replace Controller PCB
Change Controller PCB.
Note : EEPROM
EEPROM(Electronically Erasable and Programmable Read Only Memory) is a non- volatile memory which keeps memorized information even if power is turned off. It can change the contents electronically.
To change the contents, it uses higher voltage than normal, and it can not change a partial contents. (Rewriting shall be done upon erasing the all contents.)
There is a limit in a number of rewriting. 