Daikin GYEQ20AN Service Manual page 177

SiAUY361411EA
42
Inter-Unit Communication Failure
Sub-code 0: Unable to communicate between DCBL circuit boards for 20 seconds or longer
Description
Sub-code 1: Unable to communicate between sub circuit boards for 20 seconds or longer
of the failure
Sub-code 2: Abnormal sub circuit board ROM
Power supply failure; harness failure; main circuit board failure; power supply circuit board failure;
Possible
causes DCBL circuit board failure; sub circuit board failure
of the failure
Flow chart
Sub-Code 0
Is Supply Voltage Normal?
YES
Is DCBL Circuit Board
Powered ON?
(Is LED10 Flashing?)
YES
Are the harness connections
of the main circuit board's CN21 and
the DCBL main circuit board's CN210
(including high power CN211)
operating normally?
YES
Sub-Code 1
Is Sub-Circuit Board
Powered ON?
(Is LED Flashing?)
YES
Is Harness For Connecting
Main Circuit Board's CN22 And
Sub-Board's CN319
Non-Defective?
YES
Sub-Code 2
Change Sub-Circuit Board.
Troubleshooting
NO
NO
Is Supply Voltage For Power
Supply Circuit Board's CN104 And
DCBL Circuit Board's CN201
Non-Defective?
YES
NO
NO
Is Supply Voltage For Power
Supply Circuit Board's CN106 And
Sub-Circuit Board's CN202
Non-Defective?
YES
NO
Check Input/Output Voltage Of
Outdoor/Indoor Unit Breaker.
Check Power Supply Harness.
NO
Change Power Supply
Circuit Board.
Change DCBL Circuit Board.
Correct Harness Connections.
Change DCBL Circuit Board.
Change Main Circuit Board.
Check Power Supply Harness.
NO
Change Power Supply
Circuit Board.
Change Sub-Circuit Board.
Change Harness Connections.
Change Sub-Circuit Board.
Change Main Circuit Board.
025910-01EN02
Flow Charts for Troubleshooting
Error
U3
code
166