14
8-3. 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 the OPERATION INDICATOR lamp flashing.
No.
1
2
4
5
6
Symptom
Indication
Condition
Remedy
0.5-second ON
0.5-second OFF
Mis-Wiring
Outdoor
thermistors
Outdoor
control
system
Indoor coil
thermistor
3 minutes after power supply turns ON, when
serial signal is not received.
<Thermistor short>
Thermistors are abnormal when they short
after compressor start-up.
<Thermistor open>
Thermistors are abnormal when they open
after compressor start-up.
However, discharge temperature thermistor is
abnormal when open circuit is detected more
than 10 minutes after compressor start-up.
Nonvolatile memory data cannot be read
properly on deicer P.C. board.
• Shortage of refrigerant
• Replace the deicer P.C.
board.
Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
• Replace the deicer P.C.
board.
Refer to outdoor unit service
manual.
• Refer to 8-5.
D
"How to check
mis-wiring ".
3
Indoor fan
motor.
7
Low
discharge
temperature
protection
Discharge temperature has been 50
:
or less
for 20 minutes.
Abnormal
point
Outdoor unit
does not
operate.
Room
tempera-
ture
thermistor
2-time flash
2.5-second OFF
Detect Indoor coil/room temperature
thermistor short or open circuit every 8
seconds during operation.
• Refer to the characteristics of
indoor coil thermistor,
sub indoor coil thermistor,
and room temperature
thermistor on 8-6.
3-time flash
2.5-second OFF
Indoor fan
motor repeats
12 seconds
ON and 3
minutes OFF.
When the
indoor fan
motor breaks,
the fan keeps
stopping.
Rotational frequency feedback signal is not
emitting during 12-second indoor fan
operation.
• Refer to 8-5.
A
"Check of
indoor fan motor".
4-time flash
2.5-second OFF
Indoor
control
system
Nonvolatile memory data cannot be read
properly on indoor electronic control P.C.
board.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
• Replace the indoor electronic
control P.C. board.
6-time flash
2.5-second OFF
• Refer to "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
Refer to outdoor unit service
manual.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
MS-A30VD
MU-A30VD
MU-A30VD
MU-A30VD
7-time flash
2.5-second OFF
10-time flash
2.5-second OFF
Operation Indicator
Lighted
Not lighted
· Flashing of the OPERATION INDICATOR lamp (the left-hand side lamp) indicates
possible abnormalities.
· The OPERATION INDICATOR lamp (the left-hand side lamp) is lighting during
normal operation.
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OB400C
