-143-
(In the case of M-NET remote controller)
Symptom
Cause
Checking method & countermeasure
1
2
Despite pressing of
remote controller
ON/OFF switch,
operation does not
start and there is no
electronic sound.
(No powering signal
appears.)
At about 10 seconds
after turning remote
controller operation
switch ON, the
display distinguishes
and the operation
stops.
1) M-NET transmission power source is not supplied
from outdoor unit.
Main power source of outdoor unit is not
connected.
Disconnection of connector on outdoor unit circuit
board.
Main board
: CNS1, CNVCC3
INV board
: CNAC2, CNVCC1, CNL2
Faulty power source circuit of outdoor unit.
• Faulty INV board,
• Blown fuse (F1 on INV board)
• Broken diode stack
• Broken resistor (R1) for rush current protection
2) Short circuit of transmission line.
3) Erroneous wiring of M-NET transmission line at outdoor unit.
Transmission line disconnection from terminal block.
Erroneous connection of indoor/outdoor transmission line to
TB7.
4) Disconnection of transmission wiring at remote controller.
5) Faulty remote controller.
The cause of 2) and 3) is
displayed with self-diagnosis
LED for 7102 error.
1) Power source is not fed to indoor unit from transformer.
1
Main power source of indoor unit is not turned on.
2
Disconnection of connector (CND, CNT, CN3T) on indoor controller board.
3
4
Faulty or disconnected transformer of indoor unit.
5
Faulty indoor controller board.
2) Faulty outdoor control circuit board uncontrolled.
As normal transmission fails between indoor and outdoor units, outdoor unit model can not be
recognized.
Checking method & countermeasure
a) Check transmission terminal block of
remote controller for voltage.
i) In case of 17 ~ 30V
Faulty network remote controller
ii) In case of less than 17V
See “Transmission Power Circuit
(30V) Check Procedure”.
Check indoor LED3
Lighting?
Check for the change of LED
display by operating dip switch
SW1 for self-diagnosis.
Extinguishing or
unable to confirm
Check indoor unit
power source terminal
block voltage
AC 220~240V?
Check fuse on circuit
board
Blown?
Check connection of con-
nector (CND, CNT, CN3T)
Disconnected
Check transformer
resistance value
Within rated?
Check self-diagnosis
function of outdoor unit
Changed?
Faulty indoor
controller board
Check main power source
of power source wiring.
Apply power
source again.
Check 220V~240V
circuit for short circuit
and ground fault.
Improper connector
connection
Check cause of trans-
former disconnection.
•Ground fault on circuit
board
•Ground fault on
sensor, LEV
Check self-diagnosis function af-
ter powering outdoor unit again.
Changed?
Accidental
trouble
Faulty outdoor unit
control circuit board
Repair
f
NO
YES
YES
NO
NO
YES
YES
NO
NO
YES
YES
Lighting
❇
1 Check the transformer in accordance with the “TROUBLE SHOOTING” in the indoor unit’s service handbook.
NO
❇
1
Blown fuse on indoor controller board.
aulty point.
1
2
3
1
2
