Mitsubishi MS09NW Service Manual page 32

11-2 Instruction of troubleshooting
Indoor unit oper-
ates. Outdoor unit
doesn't operate.
Outdoor unit
Outdoor unit
does not
operates in
operate even
only Test
in Test Run
Run mode.
mode.
Refer to
Check room
"Check of
temperature
outdoor unit"
thermistor.
on page 36.
11-2-1 troubleshooting check table
Operation Indicator
Look at the left lamp flash for the self check table.
w Before taking measures make sure that the symptom reappears, for accurate troubleshooting.
Self check table
Abnormal
NO.
point
Indoor coil
2-time flash
thermistor
1
Room
tempera-
ture ther-
2.5-second OFF
mistor
MS09NW only
3-time flash
Indoor fan
2
motor
2.5-second OFF
32
Indoor unit
dosen't
receive the
signal from
remote
controller.
Refer to
B
"Check of
receiver P.C.
board" on
page 35.
D
Refer to
"Check of indoor
fan motor" on
page 34.
Indication
Outdoor unit
does not run.
Indoor fan
repeats 12 sec-
onds ON and 3
minutes OFF.
When the indoor
fan breaks, the
fan keeps stop-
ping.
Start
MS12NN
Operation monitor lamp on
MS15NN
the indoor unit is flashing
MS17NN on and off.
When the
remote controller
is pressed or
when the
Emergency 2-time flash
operation switch
2.5-second OFF
is pressed,the
fan does not
MS09NW only
rotate,with
3-time flash
Operation indi-
cator lamp on.
2.5-second OFF
Cause:Indoor unit
2-times-Room temperature/Indoor coil thermistor trouble.
3-times-Indoor fan motor trouble
Check indoor coil
A
thermistor. Refer
to"Test point dia-
gram and voltage"
on page 37 and 38.
Symptom Detect method
Detects Indoor coil/room tem-
perature thermistor short or
open circuit every 2 seconds
during operation.
When rotational frequency
feedback signal is not emit
during 12-second indoor fan
operation
Indoor unit doesn't
receive the signal
from remote con-
troller.
Also, operation
monitor lamp
doesn't flash,
when the emer-
gency operation
switch is pressed.
C
Refer to "Check
of indoor electric
control P.C. board"
on page 36.
Check room temperature.
Refer to"Test point dia-
gram and voltage" on
page 37 and 38.
Repair
Check thermistor calibration
Reconnect connector
Check indoor board
Disconnect connector CN211 and then
check connector CN121 - to make
2
3
sure rotational frequency feedback signal
of 1.5V or over exists.
Check indoor electronic control P.C.
board.
Check indoor fan motor
Reconnect conector