Mitsubishi Electric NTXMMX A AA Series Service Manual page 27

9-4. 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 blinks.
0.5-second ON
Miswiring
1 or serial
signal
0.5-second OFF
Indoor coil
Left lamp blinks.
thermistor
2-time blink
2
Room
temperature
2.5-second OFF
thermistor
Left lamp blinks.
3-time blink
Indoor fan
3
motor
2.5-second OFF
Left lamp blinks.
Indoor
4-time blink
4
control
system
2.5-second OFF
Left lamp blinks.
5-time blink
Outdoor
5
power
system
Left lamp blinks.
6-time blink
Outdoor
6
thermistors
Left lamp blinks.
7-time blink
Outdoor
7
control
system
Left lamp blinks.
9-time blink
Drain
8
pump
2.5-second OFF
Left lamp blinks.
14-time blink or more
Other
9
abnormality
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 blinking.
OBHT802B
· Blinking of OPERATION INDICATOR lamp (left-hand side lamp) indicates
Lit
abnormalities.
Blinking
Not lit
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.
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 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 the outdoor electronic control P.C. board.
• Float sensor is open.
• Float sensor detects abnormal water level.
An abnormality other than above mentioned is
detected.
27
Remedy
• Refer to 9-6. "How to check
miswiring and serial signal
error".
• Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
on 9-7.
• Refer to 9-6. "Check of
indoor fan motor".
• Replace the indoor electronic
control P.C. board.
• Refer to "Check of inverter/
compressor".
• Check the stop valve.
Refer to outdoor unit service
manual.
• 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.
• Check the float sensor
characteristics.
• Check the drain pump.
• Check the drain pipe.
• Check the connectors of float
sensor and the drain pump.
• Refer to 9-6. "Check of float
sensor".
• Check the abnormality in
detail using the failure mode
recall function.
Refer to outdoor unit service
manual.