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10-2. Instruction of troubleshooting
Start
Indoor unit
operates.
Outdoor unit
doesn't
operate.
Indoor unit
doesn't receive
the signal from
remote controller.
Indoor unit
operates.
Outdoor unit
doesn't operate
normally.
OPERATION
INDICATOR
lamp on the
indoor unit is
flashing on
and off.
Outdoor unit
operates in
only Test Run
operation.
Outdoor unit
doesn't
operate
even in
Test Run
operation.
Indoor unit
operates,
when the
EMERGENCY
OPERATION
switch is
pressed.
Indoor unit
doesn't operate,
when the
EMERGENCY
OPERATION
switch is
pressed.
Check room
temperature
thermistor.
Refer to 10-5
"Test point
diagram and
voltage".
Refer to 10-4.
A "Check of
outdoor unit".
Refer to
"Check of
remote
controller
and receiver
P.C. board".
Cause:
Indoor/Outdoor unit
• Mis-wiring or
trouble of serial
signal
2-time flash
Cause:
Indoor unit
• Trouble of
room temp-
erature/
indoor coil
thermistor
3-time flash
Cause:
Indoor unit
• Trouble of
indoor fan
motor
6-time flash
Cause:
Outdoor unit
• Trouble of
thermistor
in outdoor
unit
7-time flash
Cause:
Outdoor unit
• Trouble of
outdoor
control
system
Check room
temperature
thermistor
and indoor
coil thermis-
tor.
Refer to 10-5
"Test point
diagram and
voltage".
Refer to
"Check of
indoor fan
motor".
Refer to 10-4.
E"Check of
outdoor
thermistor".
Replace the
deicer
P.C. board.
Refer to 10-4. D
"How to check
mis-wiring and
serial signal
error (When
outdoor unit
doesn't work)".
W1
1. Check indoor /
outdoor
connecting wire.
2. Refer to
"Check of indoor
electronic control
P.C. board".
Outdoor unit
doesn't
stop even
if indoor unit
stops.
Unit doesn't
operate
normal
operation in
COOL or
HEAT mode.
Refer to 10-4.
B "Check of
outdoor unit".
Refer to 10-4.
C "Check of
R.V. coil".
W1.<The case of the trouble of the serial signal>
When the power is turned off and then turned on again, the indication shows “the trouble of mis-wiring”.
As for indoor unit
MSC type,
refer to service
manual OB385
or OB393.
Flash on and off at
0.5-second intervals
4-time flash
Cause:
Indoor unit
• Trouble of
indoor unit
control
system
Replace the
indoor
electronic
control
P.C. board.
MUH-GA20VB -
MUH-GA25VB -
MUH-GA35VB -
E1
E1
E1
OB387-1.qxp 05.2.21 10:03 AM Page 23