42
10-3. TROUBLESHOOTING CHECK TABLE
No.
Symptom
LED indication
Abnormal point/
Condition
Condition
Remedy
1
Outdoor unit
does not op-
erate.
1-time blink every
2.5 seconds
Outdoor power sys-
tem
Overcurrent protection cut-out operates 3 consecutive times
within 1 minute after the compressor gets started.
• Reconnect connector of compres-
sor.
• Refer to 10-5. "How to check
inverter/compressor".
• Check stop valve.
2
Outdoor thermistors
Discharge temperature thermistor, fin temperature thermistor,
defrost thermistor, P.C. board temperature thermistor, outdoor
heat exchanger temperature thermistor or ambient tempera-
ture thermistor shorts or opens during compressor running.
• Refer to 10-5. "Check of outdoor
thermistors".
3
Outdoor control sys-
tem
Nonvolatile memory data cannot be read properly.
(The upper lamp of the OPERATION INDICATOR lamp on the
indoor unit lights up or blinks 7-time.)
• Replace inverter P.C. board.
4
6-time blink
2.5 seconds OFF
Serial signal
The communication fails between the indoor and outdoor unit
for 3 minutes.
• Refer to 10-5. "How to check
miswiring and serial signal error.
5
11-time blink
2.5 seconds OFF
Stop valve/
Closed valve
Closed valve is detected by compressor current.
• Check stop valve.
6
16-time blink
2.5 seconds OFF
4-way valve/
Pipe temperature
The 4-way valve does not work properly.
The indoor coil thermistor detects an abnormal temperature.
• Refer to 10-5. "Check of R.V.
coil".
• Replace the inverter P.C. board.
7
17-time blink
2.5 seconds OFF
(
MUZ-HM09/12/15/18/
24NA(2) -
U1
MUZ-HM09/12/15/18/
24NAH
MUZ-HM09/12/15/18NA
-
U2
)
Outdoor refrigerant
system abnormality
A closed valve and air trapped in the refrigerant circuit are
detected based on the temperature sensed by the indoor and
outdoor thermistors and the current of the compressor.
• Check for a gas leak in a
connecting piping etc.
• Check the stop valve.
• Refer to 10-5. “Check of outdoor
refrigerant circuit”.
8
'Outdoor unit
stops and
restarts 3
minutes later'
is repeated.
2-time blink
2.5 seconds OFF
Overcurrent protec-
tion
Large current flows into the power module (IPM) (
MUZ-
HM09/12NA(2) -
U8
)/(IC700) (
MUZ-HM09/12/15/18/24NA(2)
-
U1
MUZ-HM09/12/15/18/24NAH MUZ-HM09/12/15/18NA
-
U2
).
When overcurrent protection occurs within 10 seconds after
compressor starts, compressor restarts after 15 seconds
(
MUZ-HM09/12NA
).
• Reconnect connector of compres-
sor.
• Refer to 10-5. "How to check
inverter/compressor".
• Check stop valve.
9
3-time blink
2.5 seconds OFF
Discharge tem-
perature overheat
protection
Temperature of discharge temperature thermistor exceeds
241°F (116°C), compressor stops. Compressor can restart if
discharge temperature thermistor reads 212°F (100°C) or less
3 minutes later.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
10
4-time blink
2.5 seconds OFF
Fin temperature /
P.C. board tem-
perature thermistor
overheat protection
Temperature of the fin temperature thermistor on the heat sink
exceeds 167 - 176°F (75 - 80°C) (
MUZ-HM09/12NA(2) MUZ-
HM09/12NAH
)/167 - 187°F
(75 - 86°C) (
MUZ-HM15/18/24NA(2) MUZ-HM15/18/24NAH
)
or temperature of P.C. board temperature thermistor on the
inverter P.C. board exceeds 158 - 167°F (70 - 75°C) (
MUZ-
HM09/12NA(2) MUZ-HM09/12NAH
)/162 - 185°F (72 - 85°C)
(
MUZ-HM15/18/24NA(2) MUZ-HM15/18/24NAH
).
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 10-5. "Check of outdoor
fan motor".
11
5-time blink
2.5 seconds OFF
High pressure pro-
tection
Indoor coil thermistor exceeds 158°F (70°C) in HEAT mode.
Defrost thermistor exceeds 158°F (70°C) in COOL mode.
• Check refrigerant circuit and refrig-
erant amount.
• Check stop valve.
12
8-time blink
2.5 seconds OFF
Compressor syn-
chronous abnormal-
ity
The waveform of compressor current is distorted.
• Reconnect connector of compres-
sor.
• Refer to 10-5. "How to check
inverter/compressor".
13
10-time blink
2.5 seconds OFF
Outdoor fan motor
Outdoor fan has stopped 3 times in a row within 30 seconds
after outdoor fan start-up.
• Refer to 10-5. "Check of outdoor
fan motor.
• Refer to 10-5. "Check of inverter
P.C. board.
14
12-time blink
2.5 seconds OFF
Each phase current
of compressor
Each phase current of compressor cannot be detected nor-
mally.
• Refer to 10-5. "How to check
inverter/compressor".
15
13-time blink
2.5 seconds OFF
Bus-bar voltage
(DC)
Bus-bar voltage of inverter cannot be detected normally.
• Refer to 10-5. "How to check in-
verter/compressor".
OBH747F
