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Symptoms
< Diagnostic Method and Remedy >
Causes
3
'HO' on the display
cannot be turned
off, and the switch
does not respond.
1) M-NET Transmission is powered by the outdoor unit
1
Main switch on the outdoor unit is off
2
Connectors on the main board of the outdoor unit are unplugged
Main controller board ·············· CNS1,CNVCC3
Inverter board ························· CNDC2, CNVCC2, CNL2
Gate-amp terminal board ········ CNDC1
3
Faulty outdoor power supply circuit
• Blown fuse on G/A board
• Faulty Inverter board
• Damaged diode stack
• Surge breaker resistance (R1) Loss
2) Shorted transmission line
3) Faulty wiring of M-NET transmission line on the outdoor unit
1
Torn transmission line, disconnected line from terminal
2
Indoor transmission line is accidentally connected to TB7
4) Torn M-NET line on the indoor unit
5) Disconnected lines or unplugged connectors between M-NET
transmission terminal (TB5) and Indoor controller board CN2M
6) MA remote controller line is wired incorrectly
1
Short-circuited MA controller line
2
MA remote controller line (No.2) is torn or disconnected from
terminal board
3
Faulty wiring among grouped units.
4
MA remote controller line is accidentally connected to TB5
5
M-NET transmission line is accidentally connected to TB15
7) A different address other than the indoor unit a50 is used
for the outdoor unit
8) The address of the indoor unit is set above 51
9) MA remote controller is set as subordinate
10) Faulty indoor controller board (MA remote controller
communication circuit)
11) Faulty remote controller
If one of the items 1)~4) is the
cause of the problem, LED 5 on
the indoor control board will be
off.
If one of the items 2), 3), or 5) is
the cause of the problem, Error
Code 7102 will be displayed on
the self-diagnosis LED on the
outdoor unit.
YES
NO
YES
NO
YES
YES
NO
NO
Self-Diagnoses LED Check
Check the voltage of trans-
mission terminal board TB15
Faulty MA remote
controller or indoor
controller board
Check items
2) 3) and 6)
Check item 4)
9~12V?
Check items
5), 6), 8), and 9)
Fix any problems
found
Fix any problems
found
Check item 1)
Are all units in the
refrigerant circuit experiencing
the same problem?
Is Error Code 7102 displayed?
Was the
problem found?