Mitsubishi Electric MUFZ-KJ-NAHZ Series Service Manual page 24

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