Mitsubishi Electric MSZ-GB50VA Service Manual page 15

9-4. Troubleshooting check table
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and the following detection method has detected an abnormality (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.
OPERATION INDICATOR
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
· 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.
Condition
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 the outdoor electronic control P.C. board.
When the indoor coil or the room temperature
thermistor is short or open 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.
When it consecutively occurs 3 times that the
compressor stops for overcurrent 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 the outdoor electronic control P.C. board.
An abnormality other than above mentioned is
detected.
15
Correspondence
• Refer to 9-6.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 9-7.the
characteristics of indoor coil
thermistor, and the room
temperature thermistor.
• Refer to 9-6.A "Check of
indoor fan motor".
• Replace the indoor electronic
control P.C. board.
• Refer to "How to check
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 for outdoor
unit.