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1. Troubleshooting check table
• The following indication applies regardless of shape of the indicator.
Operation Indicator
Lighted
Not lighted
Before taking measures, make sure that the symptom reappears, for accurate troubleshooting.
Self check table
Abnormal
No.
Operation indicator lamp
point
0.5-second ON
Mis-Wiring
or Serial
1
signal
0.5-second OFF
Indoor coil
2-time flash
thermistor
2
Room
temperature
2.5-second OFF
thermistor
3-time flash
Indoor fan
3
motor
2.5-second OFF
4-time flash
Indoor
control
4
system
2.5-second OFF
5-time flash
Outdoor
power
5
system
2.5-second OFF
6-time flash
Outdoor
6
thermistors
7-time flash
Outdoor
control
7
system
Right lamp flashes.
Operation Indicator
MXZ type
Operation
8
mode
Lighted
2.5-second OFF
setting
Blinking
NOTE : When the indoor unit has started operation and the above 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.
OB345A
· 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.
Symptom
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Indoor fan repeats
12 seconds ON
and 3minutes OFF.
When the indoor
fan breaks, the fan
keeps stopping.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
2.5-second OFF
Outdoor unit
does not
operate.
2.5-second OFF
Outdoor unit
operates but
indoor unit
does not
operate.
Detection method
3 minutes after power supply turns ON, when
serial signal is not received.
Detect Indoor coil/room temperature
thermistor short or open circuit every 8
seconds during operation.
When rotational frequency feedback signal is
not emit during 12-second indoor fan
operation.
When it cannot properly read data in the
nonvolatile memory of the indoor electronic
control P.C. board.
When compressor has stopped due to over
current protection or start-up failure protection
3 times in a row within 5 seconds after start-
up.
<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.
When it cannot properly read data in the
nonvolatile memory of outdoor electronic
control P.C. board.
When the operation mode of each indoor unit
is differently set to COOL(includes DRY) and
HEAT at same time, the operation mode of
indoor unit that has operated at first has the
priority.
13
Checkpoint
• Refer to D "How to check
mis-wiring and serial signal
error" on page 17.
• Refer to the characteristics of
main indoor coil thermistor,
sub indoor coil thermistor,
and room temperature
thermistor on page 18 and 19.
• Refer to A "Check of
indoor fan motor" on page 15.
• Check the indoor electronic
control P.C. board.
• Refer to "Check of inverter/
compressor".
Refer to service manual
OB346 or OB319.
• Shortage of refrigerant
• Replace the outdoor control
P.C. board.
Refer to "Check of outdoor
thermistor".
Refer to service manual
OB346 or OB319.
• Replace the outdoor
electronic control P.C. board.
Refer to service manual
OB346 or OB319.
• Unify the operation mode.
Refer to service manual
OB319.
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