22
1. Troubleshooting check table
• The following indication applies regardless of shape of the indicator.
Operation Indicator
flashing
Before taking measures, make sure that the symptom reappears, for accurate troubleshooting.
Self check table
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.
No.
1
2
4
6
7
Symptom
Operation indicator lamp
Detection method
Checkpoint
0.5-second ON
0.5-second OFF
Mis-Wiring
Outdoor
thermistor
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.
MUH type
When it cannot properly read data in the
nonvolatile memory of the deicer P.C. board,
outdoor unit stops [and restarts 3 minutes
later(MUH-24WV).]
MXZ type
When it cannot properly read data in the
nonvolatile memory of the outdoor electronic
control P.C.board.
• Shortage of refrigerant
• Check the deicer P.C.
board.
Refer to "Check of outdoor
thermistor". Refer to service
manual OB322.
MUH type
• Check the deicer P.C. board.
Refer to service manual
OB322.
MXZ type
• Check the outdoor electronic
control P.C. board.
Refer to service manual
OB319.
• Refer to
D
"How to check
mis-wiring " on page 26.
3
Indoor fan
motor
8
MUH-A30WV
Low
discharge
temperature
protection
MXZ type
Outdoor
refrigerant
system
error
MUH-A30WV
When discharge temperature has been 50
:
or less on cool operation, or has been 49
:
or
less on heat operation for 20 minutes.
MXZ type
When the compressor operation has been
interrupted by LEV protection continuously 5
minutes, the compressor stops operation.
Abnormal
point
Outdoor unit
does not
operate.
Room
temperature
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
main indoor coil thermistor,
sub indoor coil thermistor,
and room temperature
thermistor on page 27.
3-time flash
2.5-second OFF
Indoor fan repeats
12 seconds ON
and 3minutes OFF.
When the indoor
fan breaks, the fan
keeps stopping.
When rotational frequency feedback signal is
not emitting during 12-second indoor fan
operation.
• Refer to
A
"Check of
indoor fan motor" on page 24.
4-time flash
2.5-second OFF
Indoor
control
system
When it cannot properly read data in the
nonvolatile memory of the indoor electronic
control P.C. board.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
• Check the indoor electronic
control P.C. board.
6-time flash
2.5-second OFF
MUH-A30WV
• Refer to "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
Refer to service manual
OB322.
MXZ type
• Refer to "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
• Check outdoor electronic
control P.C. board.
Refer to service manual
OB319.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
5
When the compressor operation is
continuously three times interrupted by over
current protection within 1 minute after start-up ,
it stops operation.
Outdoor unit
does not
operate.
• Check the inverter output.
Check the compressor.
5-time flash
2.5-second OFF
Operation Indicator
MXZ type
Operation
mode
setting
9
Lighted
Flashing
Outdoor unit
operates but
indoor unit
does not
operate.
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.
• Unify the operation mode.
7-time flash
2.5-second OFF
10-time flash
2.5-second OFF
Outdoor
power
system
2.5-second OFF
· Flashing of the OPERATION INDICATOR lamp (on the left-hand side) indicates possible
abnormalities.
· The OPERATION INDICATOR lamp (on the left-hand side) is lighting during normal operation.
OB321-1.qxp 03.11.13 4:03 PM Page 22
