Mitsubishi Electric MSC-GE20VB Service Manual page 23

10-2. INSTRUCTION OF TROUBLESHOOTING
Start
Indoor unit
operates.
Outdoor unit
does not
operate.
Outdoor unit MUH/MUX
operates only Outdoor unit
in "Test run does not
operation". operate
even in
"Test run
operation".
Check room Refer to
temperature
"Check of
thermistor.
outdoor unit".
Refer to 10-6.
"Test point
diagram and
voltage".
MUH/MXZ
2-time flash
Flash ON and
Cause:
OFF at 0.5-
Indoor unit
second intervals
• Trouble of
Cause: Indoor/
room temp-
outdoor unit
erature/
• Mis-wiring/or
indoor coil
trouble of
thermistor
serial signal
Refer to Check room
10-5. or
temperature
"How to
thermistor
check
and indoor
mis-wiring/
coil thermis-
and serial tor.
signal error Refer to 10-6.
(When "Test point
outdoor unit diagram and
does not voltage".
work)".
1.<The case of the trouble of the serial signal>
When the power is turned off and turned on again, the indication shows "the trouble of mis-wiring".
2."Test run operation" means the operation within 30 minutes after EMERGENCY OPERATION switch is pressed.
Refer to outdoor unit service manual.
OBH529A
Indoor unit
operates.
Outdoor unit
does not operate
normally.
Outdoor unit MUH/MXZ
does not Unit does not
stop even operate
if indoor unit normal
stops. operation in
COOL or
HEAT mode.
MU Refer to
Check of wiring "Check of
R.V. coil".
diagram of
outdoor unit
MUH
Refer to
"Check of
outdoor unit".
3-time flash
4-time flash
Cause: Cause:
Indoor unit
Indoor unit
• Trouble of
• Trouble of
indoor unit
indoor fan
control
motor
system
Replace the
Refer to
indoor
10-5.
electronic
"Check of
control
indoor fan
P.C. board.
motor".
Indoor unit
does not receive
the signal from
remote controller.
Indoor unit Indoor unit
operates, when does not operate,
the EMERGENCY when the
OPERATION EMERGENCY
switch is pressed. OPERATION
switch is pressed.
1. Check indoor/
Refer to 10-5.
"Check of outdoor
remote controller connecting wire.
and receiver 2. Refer to 10-5.
P.C. board". "Check of indoor
electronic control
P.C. board".
MUH/MXZ
MXZ MUH/MXZ
7-time flash
5-time flash
6-time flash
Cause:
Cause:
Cause:
Outdoor unit Outdoor unit
• Trouble of
• Outdoor • Trouble of
thermistor
power
in outdoor
system
unit
abnormality
Refer to
Replace the
Refer to
"Check of
"Check of deicer
inverter/
outdoor P.C. board
compressor"
thermistor" and others.
and "Check
and others.
of power
supply".
23
OPERATION INDICATOR
lamp on the indoor unit is
flashing ON and OFF.
10-time flash
Cause:
Outdoor unit
Outdoor unit MXZ
• Outdoor
outdoor refrigerant
system
control
abnormality
system
Refer to
outdoor
refrigerant
system
related items.
Indoor unit
operates.
But indoor
unit does not
blow out
cool air.
MUX-2A28/2A59/3A60/
3A63/2A70/4A73VB
Refer to
"Check of
indoor/outdoor
units' connection
and outdoor
unit".