Troubleshooting Check Table - Mitsubishi Electric MSH-07NV Service Manual

10-2-1 troubleshooting check table

Before taking measures, make sure that the symptom reappears, for accurate troubleshooting.
Self check table
Abnormal
NO.
point
0.5-second ON
Mis-wiring
0.5-second OFF
1
1-time flash
Serial sig-
nal
2.5-second OFF
Indoor coil
2-time flash
thermistor
2
Room
tempera-
ture ther- 2.5-second OFF
mistor
3-time flash
Indoor fan
3
motor
2.5-second OFF
6-time flash
Outdoor
4
thermistor
5-time flash
Outdoor
5
power
system
7-time flash
Outdoor
6
control
P.C. board
10-time flash
Outdoor
7
control
P.C. board
Outdoor
8 control
light
P.C. board
flash
The indication is shown only when the indoor unit connects with the outdoor unit MXZ-32NV-
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
Outdoor unit
does not run
2.5-second OFF
Outdoor unit
does not run
2.5-second OFF
Outdoor unit
does not run
2.5-second OFF
Outdoor unit
runs but the
2.5-second OFF
indoor unit does
not run.
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.
Detect 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.
When the compressor opera-
tion is continuosly three times
interruped by overcurrent pro-
tection within 1 minute after
start-up , it stops operation.
The outdoor unit stops opera-
tion when it cannot properly
read data in the nonvolatile
memory of the outdoor control
P.C.board.
When the indoor unit detects
drain abnormality and the
indoor coil temperature is too
low.
When the operation mode of
each rooms is setted
COOL(includes DRY) and
HEAT at same time, it take
precedence the operation
mode runs first.
Check point
Check wiring (visual check and conductiv-
ity check).
Check indoor electronic control
P.C.board.
Check outdoor DEICER P.C. board.
Check electrical parts.
Check thermistor calibration.
Reconnect connector.
Check indoor electronic control P.C.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.
Shortage of refrigerent.
Check outdoor DEICER P.C. board.
Check the inverter output.
Check the compressor.
Check the outdoor control P.C.board.
Check the drain punp.
Check the drain sensor.
Check LEV.
Adjust the operation mode.
.
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