Service manual

24
10-3. TROUBLESHOOTING CHECK TABLE
• Refer to 10-5. "How to
check mis-wiring ".
No.
1
2
4
7
8
SymptomOperation indicator lamp Condition Remedy
0.5-second ON
0.5-second OFF
MUH-GE
Mis-Wiring
MUH/
MXZ
Outdoor
thermistor
MUH/
MXZ
Outdoor
control
system
Indoor coil
thermistor
3 minutes after power supply turns ON,
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.
It cannot properly read data in the nonvolatile
memory of the outdoor P.C. board.
• Shortage of refrigerant
• Check the deicer P.C. board
and others.
Refer to "Check of outdoor
thermistor". Refer to outdoor
service manual.
• Check the deicer P.C. board
and others.
Refer to outdoor service
manual.
3
Indoor fan
motor
Abnormal
point
Outdoor unit
does not
operate.
Room
temperature
thermistor
2-time flash
2.5-second OFF
Indoor coil/room temperature thermistor
detects short or open circuit every 8 seconds
during operation.
• Refer to the characteristics
of indoor coil thermistor, and
room temperature thermistor
on 10-6.
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.
The rotational frequency feedback signal is
not emitted for 12 seconds after indoor fan
motor is operated.
• Refer to 10-5. "Check of
indoor fan motor".
4-time flash
2.5-second OFF
Indoor
control
system
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
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
6
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.
9
MXZ
Outdoor
refrigerant
system
error
The compressor operation has been
interrupted by LEV protection continuously 5
minutes, the compressor stops operation.
Outdoor unit
does not run.
• Refer to "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
• Check outdoor electronic
control P.C. board.
Refer to outdoor unit service
manual.
Operation Indicator
MXZ
Operation
mode
setting
Lighted
Flashing
Outdoor unit
operates but
indoor unit
does not run.
10-time flash
2.5-second OFF
2.5-second OFF
E
7-time flash
2.5-second OFF
0.5-second ON
0.5-second OFF
MUH-GA/
MXZ
Mis-wiring/
or Serial
signal
• Check switch SW2- .(MU &
MUX type or MUH & MXZ
type)
• Check wiring (visual check
and conductivity check).
• Check indoor electronic
control P.C.board.
• Check outdoor DEICER P.C.
board and others.
• Check electrical parts.
Outdoor unit
does not run.
Serial signal from outdoor unit stops for 4 to 5
seconds.
5
Outdoor unit
does not run.
The compressor operation is
continuously three times interrupted by over
current protection within 1 minute after
start-up , it stops operation.
• Check the inverter output.
• Check the compressor.
5-time flash
2.5-second OFF
MXZ
Outdoor
power
system
Lighted
Not lighted
• 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.
· Flashing of the OPERATION INDICATOR lamp (the left-hand side lamp)
indicates possible abnormalities.
OBH529A