Mitsubishi Electric MSH-XV07UV Service Manual page 42

1. Troubleshooting check table
•The following indication applies regardless of shape of the indicator.
flashing
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
tempera-
2.5-second OFF
ture ther-
mistor
3-time flash
Indoor fan
3
motor
2.5-second OFF
6-time flash
Outdoor
4
thermistor
· Flashing of the OPERATION INDICATOR lamp (on the left-hand side)
indicates possible abnormalities.
· The OPERATION INDICATOR lamp (on the left-hand side) is lighting during
normal operation.
Indication
Outdoor unit
does not run.
Outdoor unit
does not run.
Indoor fan motor
repeats 12 sec-
onds ON and 3
minutes OFF.
When the indoor
fan motor
breaks, the fan
keeps stopping.
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 contactor 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 8 seconds
during operation.
When rotational frequency
feedback pulse signal is not
emit during 12-second indoor
fan operation.
When the defrost thermistor
shorts or opens after the com-
pressor start-up.
42
Check point
Check wiring (visual check and conductiv-
ity check).
Check indoor electronic control
P.C.board.
Check deicer P.C. board.
Check electrical parts.
Check resistance of thermistor.
Re-connect 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.
Re-connect connector.
Check deicer P.C. board.
Check resistance of thermistor.
Re-connect connector.