Mitsubishi Electric MFZ-KA25VA Service Manual page 23

2. Indoor unit failure mode table
NOTE:Blinking patterns of this mode differs from the ones of Troubleshooting check table (10-4.).
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
Not lighted
11-time flash
2.5-second OFF
1-time flash
every 0.5-second
12-time flash
Not lighted
2.5-second OFF
13-time flash
Not lighted
2.5-second OFF
14-time flash
Not lighted
2.5-second OFF
Abnormal point
(Failure mode)
Normal
When the room temperature thermistor
Room temperature
short or open circuit is detected every 8
thermistor
seconds during operation.
When the indoor coil thermistor short or
Indoor coil thermistor
open circuit is detected every 8 seconds
(Main 1, 2 and sub)
during operation.
When the serial signal from the outdoor unit is
Serial signal error
not received for a maximum of 6 minutes.
When the rotational frequency feedback
Indoor fan motor (Upper)
signal is not emitted during 12-second the
indoor fan operation.
Indoor fan motor (Lower)
When it cannot be read properly data in the
nonvolatile memory of the indoor electronic
Indoor control system
control P.C. board.
When the indoor coil thermistor short or
Indoor coil thermistor
open circuit is detected every 8 seconds
(Main 3)
during operation.
When the damper is not located at the
designated position.
Damper
Check point
–
23
Countermeasure
–
Refer to the characteristics of the room
temperature thermistor (10-7.).
Refer to the characteristic of the main 1,2
indoor coil thermistor and the sub indoor
coil thermistor (10-7.).
Refer to 10-6.D "How to check miswiring
and serial signal error".
Refer to 10-6 A-1 "Check of indoor
fan motor (Upper)"
Refer to 10-6 A-2 "Check of indoor
fan motor (Lower)"
Replace the indoor electronic control
P.C. board.
Replace to the characteristic of the main
3 indoor coil thermistor (10-7.).
Refer to 10-6.E "Check of damper".