Mitsubishi Electric MSZ-D30NA Service Manual page 21

2. Table of indoor unit failure mode recall function
Left lamp of
Abnormal point
OPERATION
(Failure mode)
INDICATOR lamp
Not lit Normal
1-time blink every Room temperature
0.5-second thermistor
2-time blink Indoor coil thermis-
2.5-second OFF tor
3-time blink
Serial signal
2.5-second OFF
11-time blink
Indoor fan motor
2.5-second OFF
12-time blink Indoor control
2.5-second OFF system
NOTE : Blinking patterns of this mode differ from the ones of Troubleshooting check table (9-4.).
OBH501D
Condition
—
The room temperature thermistor short or open
circuit is detected every 8 seconds during
operation.
The indoor coil thermistor short or open circuit
is detected every 8 seconds during operation.
The serial signal from outdoor unit is not
received for a maximum of 6 minutes.
The rotational frequency feedback signal is not
emit during the 12 seconds the indoor fan
operation.
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
21
Remedy
—
Refer to the characteristics of the room temperature
thermistor (9-7.).
Refer to the characteristics of the main indoor coil
thermistor, the sub indoor coil thermistor (9-7.).
Refer to 9-6. "How to check miswiring and serial
signal error".
Refer to 9-6. "Check of indoor fan motor".
Replace the indoor electronic control P.C. board.