Mitsubishi Electric MSH-18NV Service Manual page 23

1. troubleshooting check table
Operation Indicator
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
signal
2.5-second OFF
Indoor coil
2-time flash
thermistor
2
Room
temperatur
2.5-second OFF
e
thermistor
3-time flash
Indoor fan
3
motor
2.5-second OFF
6-time flash
Defrost
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
Operation Indicator
Outdoor
8
control
lighting
P.C. board
flashing
The indication is shown only when the indoor unit connects with the outdoor unit MXZ-32NV-
.
MXZ-32RV-
E1
Indication
Outdoor unit
does not run.
Outdoor unit
does not run.
Indoor fan motor
repeats 12
seconds ON and
3 minutes OFF.
When the indoor
fan breaks, the
fan motor keeps
stopping.
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
indoor unit does
2.5-second OFF
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
outdoor unit stops for 4 to 5
seconds.
Detect Indoor coil/room
temperature thermistor short
or open circuit every 8
seconds during operation.
When rotational frequency
feedback signal is not emit
during 12-second indoor fan
operation.
When the defrost thermistor
shorts or opens after the
compressor start-up.
When the compressor
operation is continuously three
times interrupted by over
current protection within 1
minute after start-up , it stops
operation.
The outdoor unit stops
operation 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 set
COOL(includes DRY) and
HEAT at same time, it take
precedence the operation
mode runs first.
23
Check point
Check wiring (visual check and
conductivity check).
Check indoor electronic control
P.C.board.
Check outdoor DEICER P.C. board.
Check electrical parts.
Check resistance of thermistor.
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 connector.
Check outdoor DEICER P.C. board.
Check resistance of thermistor.
Reconnect connector.
Check the inverter output.
Check the compressor.
Check the outdoor control P.C.board.
Check the drain pump.
Check the drain sensor.
Check LEV.
Adjust the operation mode.
or MXZ-32NV- or
E1 E2