Mitsubishi Electric MUH-GA20VB-E1 Service Manual page 21

11-2. Instruction of troubleshooting
MUH-GA20VB MUH-GA25VB MUH-GA35VB
Start
Indoor unit
operates.
Outdoor unit
doesn't
operate.
Outdoor unit Outdoor unit
operates in doesn't
only Test Run operate
W
operation. even in
Test Run
operation.
Check room
Refer to 11-4.
temperature
A "Check of
thermistor.
outdoor unit".
Refer to 11-5.
"Test point
diagram and
voltage".
Flash on and off at 2-time flash
Cause:
0.5-second intervals
Indoor unit
Cause:
• Trouble of
Indoor/Outdoor unit
• Mis-wiring or
trouble of serial
signal
Refer to 11-4. D
"How to check
mis-wiring and
serial signal
error (When
outdoor unit
doesn't work)".
W1
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".
Indoor unit
operates.
Outdoor unit
doesn't operate
normally.
Outdoor unit
doesn't
stop even
if indoor unit
stops.
W
Refer to 11-4.
B "Check of
outdoor unit".
3-time flash
Cause:
Indoor unit
• Trouble of
room temp-
indoor fan
erature/
motor
indoor coil
thermistor
Check room
Refer to
temperature
"Check of
thermistor
indoor fan
and indoor
motor".
coil thermis-
tor.
Refer to 11-5.
"Test point
diagram and
voltage".
Indoor unit
doesn't receive
the signal from
remote controller.
Unit doesn't
Indoor unit
operate
operates,
normal
when the
operation in
EMERGENCY
COOL or
OPERATION
HEAT mode. switch is
pressed.
Refer to 11-4.
Refer to
C "Check of
"Check of
R.V. coil".
remote
controller
and receiver
P.C. board".
4-time flash
6-time flash
Cause:
Cause:
Indoor unit
Outdoor unit
• Trouble of
• Trouble of
indoor unit
thermistor
control
in outdoor
system
unit
Replace the
Refer to 11-4.
indoor
E"Check of
electronic
outdoor
control
thermistor".
P.C. board.
21
OPERATION
INDICATOR
lamp on the
indoor unit is
flashing on
and off.
Indoor unit
doesn't operate,
when the
EMERGENCY
OPERATION
switch is
pressed.
Refer to indoor
unit service
1. Check indoor /
manual.
outdoor
W "Test run operation"
connecting wire.
2. Refer to
means the
"Check of indoor
operation
electronic control
within 30 minutes
P.C. board".
after
EMERGENCY
OPERATION
switch is pressed.
7-time flash
Cause:
Outdoor unit
• Trouble of
outdoor
control
system
Replace the
deicer
P.C. board.