Troubleshooting Check Table - Mitsubishi Electric MFZ-KA25VA Service Manual

10-4. Troubleshooting check table

OPERATION INDICATOR
NOTE : Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
Self check table
Abnormal
No. Operation indicator lamp
point
Left lamp flashes.
0.5-second ON
Mis-Wiring
or serial
1
signal
0.5-second OFF
Outdoor
control
Left lamp lights up
2
system
Indoor coil
Left lamp flashes.
thermistor
2-time flash
3
Room
tempera-
2.5-second OFF
ture
thermistor
Left lamp flashes.
3-time flash
Indoor fan
4
motor
2.5-second OFF
Left lamp flashes.
Indoor
4-time flash
control
5
system
2.5-second OFF
Left lamp flashes.
5-time flash
Outdoor
power
6
system
Left lamp flashes.
6-time flash
Outdoor
7
thermistors
Left lamp flashes.
7-time flash
Outdoor
control
8
system
Left lamp flashes.
14-time flash
Other
9
abnormality
2.5-second OFF
Left lamp flashes.
15-time flash
Indoor
10
damper
2.5-second OFF
NOTE : When the indoor unit has started operation and the above failures are detected (the first detection after the power
ON), the indoor electronic control P.C. board turns OFF the indoor fan motor with OPERATION INDICATOR lamp
flashing.
· Flashing of OPERATION INDICATOR lamp (left-hand side lamp)
Lighted
indicates abnormalities.
Blinking
Not lighted
Symptom
Indoor unit
and outdoor
unit do not
operate.
Outdoor unit
does 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.
Indoor unit
and outdoor
unit do not
operate.
Check point
When the serial signal from the outdoor unit is
not received for a maximum of 6 minutes.
When it cannot properly read data in the
nonvolatile memory of the inverter P.C. board
or of the outdoor electronic control P.C. board.
When the indoor coil or the room temperature
thermistor is shorts or opens circuit.
When the rotational frequency feedback
signal is not emitted during the indoor fan
operation.
When it cannot properly read data in the
nonvolatile memory of the indoor electronic
control P.C. board.
The compressor stops 3 times consecutively
for over current protection or start-up failure
protection within 1 minute after start-up.
When the outdoor thermistors short or open
circuit during the compressor operation.
When it cannot properly read data in the
nonvolatile memory of the inverter P.C. board
or of the outdoor electronic control P.C. board.
An abnormality other than above mentioned is
detected.
When the damper is not located
at the designated position.
25
Countermeasure
• Refer to 10-6.D "How to check
mis-wiring and serial signal
error".
• Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor
electronic control P.C. board.
• Refer to the characteristics of
indoor coil thermistor, and the
roomtemperature thermistor
on 10-7.
• Refer to 10-6.A-1, A-2
"Check of indoor fan motor".
• Replace the indoor electronic
control P.C. board.
• Refer to "Check of inverter/
compressor".
Refer to outdoor unit service
manual.
Check the stop valve.
• Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
• Replace the inverter P.C.
board or the outdoor
electronic control P.C. board.
Refer to outdoor unit service
manual.
• Confirm the abnormality in
detail using the failure mode
recall function.
Refer to outdoor unit service
manual.
• Refer to 10-6.E "Check of
damper".