Troubleshooting Check Table - Mitsubishi Electric Mr. Slim MSH09NW Service Manual

11-2-1 troubleshooting check table

Look at the left lamp flash for the self check table.
Before taking measures, make sure that the symptom reappears, for accurate troubleshooting.
Self check table
Abnormal
NO.
point
1-second ON
Mis-wiring
1-second OFF
1
1-second ON
Serial sig-
nal
2.5-second OFF
Indoor coil
2-time flash
thermistor
2
Room
tempera-
ture ther- 2.5-second OFF
mistor
MSH09NW only
3-time flash
Indoor fan
3
motor
2.5-second OFF
6-time flash
Outdoor
4
thermistor
Indication
Outdoor unit
does not run.
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.
Outdoor unit
does not run
2.5-second OFF
Symptom Detect method
When serial signal stops for 4
to 5 seconds after 1st on of
52C relay by POWER turning
on.
When serial signal from out-
door unit stops for 4 to 5 sec-
onds.
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.
When the outdoor thermistor
shorts or opens after the com-
pressor start-up.
Check point
Check wiring (visual sheck and conductiv-
ity check).
Check indoor electronic control P.C.
board.
Check outdoor DEICER P.C. board.
Check electrical parts.
Check thermistor calibretion.
Reconnect connector.
Check indoor borad.
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.
Check outdoor DEICER P.C. board.
Check thermistor calibretion.
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