Mitsubishi Electric MFZ-KJ25VE Service Manual page 24

10-4. TROUBLESHOOTING CHECK TABLE
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after the
power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp flashes.
OPERATION INDICATOR
Abnormal
No.
Operation indicator lamp
point
Left lamp flashes.
0.5-second ON
Miswiring
or serial
1
signal
0.5-second OFF
Indoor coil
Left lamp flashes.
thermistor
2-time flash
2
Room
tempera-
2.5-second OFF
ture
thermistor
Left lamp flashes.
3-time flash
Indoor fan
3
motor
2.5-second OFF
Left lamp flashes.
Indoor
4-time flash
4
control
system
2.5-second OFF
Left lamp flashes.
5-time flash
Outdoor
5 power
system
Left lamp flashes.
6-time flash
Outdoor
6
thermistors
Left lamp flashes.
7-time flash
Outdoor
7 control
system
Left lamp flashes.
14-time flash or more
Other
8
abnormality
2.5-second OFF
Outdoor
control
9
Left lamp lights up
system
NOTE: The indoor unit may have been connected to a non-low-standby-power model outdoor unit. To use a low-standby-power
model, clear the error history by referring to "Deleting the memorized abnormal condition" described in 10-2.1. When
the error history is being cleared, the connection information also will be initialized. The indoor unit will be compatible
with a low-standby-power model after initialization. If the operation indicator lamp continues to f ash as shown in No.1
after the procedure, refer to 10-6.
OBH666C
Lighted
Blinking
Not lighted
Symptom
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
Indoor unit
and outdoor
unit do not
operate.
2.5-second OFF
Indoor unit
and outdoor
unit do not
operate.
2.5-second OFF
Indoor unit
and outdoor
unit do not
operate.
2.5-second OFF
Indoor unit
and outdoor
unit do not
operate.
Outdoor unit
does not
operate.
"How to check miswiring and serial error".
Condition
The serial signal from the outdoor unit is not
received for a maximum of 6 minutes.
The indoor unit is connected to a
low-standby-power model after once
connected to a non-low-standby-power model.
The indoor coil or the room temperature
thermistor is short or open circuit.
The rotational frequency feedback signal is
not emitted during the indoor fan operation.
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
It consecutively occurs 3 times that the
compressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.
The outdoor thermistors short or open circuit
during the compressor operation.
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the
outdoor electronic control P.C. board.
An abnormality other than above mentioned is
detected.
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the
outdoor electronic control P.C. board.
24
Remedy
• Refer to 10-6. "How to check
miswiring and serial signal
error".
• Refer to NOTE.
• Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
on 10-7.
• Refer to 10-6. "Check of
indoor fan motor".
• Replace the indoor electronic
control P.C. board.
• Refer to "Check of inverter/
compressor".
Refer to the outdoor unit
service manual.
Check the stop valve.
• Refer to "Check of outdoor
thermistor".
Refer to the outdoor unit
service manual.
• Replace the inverter P.C.
board or the outdoor electronic
control P.C. board.
Refer to the outdoor unit
service manual.
• Check the stop valve.
• Check the 4-way valve.
• Check the abnormality in
detail using the failure mode
recall function.
Refer to the outdoor unit
service manual.
• Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.