Mitsubishi Electric MSZ-A09NA Service Manual page 14

2. Indoor unit failure mode table
Left lamp of OPERATION
INDICATOR lamp
Not lighted
Room temperature
1-time flash
thermistor
every 0.5-second
2-time flash
Indoor coil thermistor
2.5-second OFF
3-time flash
Serial signal
2.5-second OFF
11-time flash
Indoor fan motor
2.5-second OFF
12-time flash
Indoor control system
2.5-second OFF
NOTE : Blinking patterns of this mode differ from the ones of Troubleshooting check table (8-4.).
Abnormal point
(Failure mode)
Normal
When the room temperature thermistor short
or open circuit is detected every 8
seconds during operation.
When the indoor coil thermistor short or open
circuit is detected every 8 seconds during
operation.
When the serial signal from outdoor unit is
not received for a maximum of 6 minutes.
When the rotational frequency feedback
signal is not emit during the 12-seconds the
indoor fan operation.
When it cannot properly read data in the
nonvolatile memory of the indoor electronic
control P.C. board.
Condition
–
Refer to the characteristics of the room
temperature thermistor (8-7.).
Refer to the characteristics of the main
indoor coil thermistor, the sub indoor coil
thermistor (8-7.).
Refer to 8-6.D "How to check mis-wiring
and serial signal error".
Refer to 8-6.A "Check of indoor fan
motor".
Replace the indoor electronic control
P.C. board.
14
Correspondence
–