29
11-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED
indication Abnormal point/
Condition
Condition Remedy
1
Outdoor unit
does not op-
erate.
1-time
fl
ash every
2.5 seconds
Outdoor power sys-
tem
Overcurrent protection cut-out operates 3 consecutive times
within 1 minute after the compressor gets started, or failure of
restart of compressor has repeated 24 times.
Reconnect connector of compres-
sor.
Refer to 11-5. "How to check in-
verter/compressor".
Check stop valve.
•
•
•
2
Outdoor thermistors Discharge temperature thermistor,
fi
n temperature thermistor,
defrost thermistor, P.C. board temperature thermistor or out-
door heat exchanger temperature thermistor shorts or opens
during compressor running.
Refer to 11-5. "Check of outdoor
thermistors".
•
3
Outdoor control sys-
tem
Nonvolatile memory data cannot be read properly.
(The upper lamp of OPERATION INDICATOR lamp of the in-
door unit lights up or
fl
ashes 7-time.)
Replace inverter P.C. board.
•
4
6-time
fl
ash
2.5 seconds OFF
Serial signal
The communication fails between the indoor and outdoor unit
for 3 minutes.
Refer to 11-5. "How to check
miswiring and serial signal error.
•
5
11-time
fl
ash
2.5 seconds OFF
Stop valve/
Closed valve
Closed valve is detected by compressor current.
Check stop valve.
•
6
14-time
fl
ash
2.5 seconds OFF
Outdoor unit
(Other abnormality)
Outdoor unit is defective.
Refer to 11-2.2. "Flow chart of the
detailed outdoor unit failure mode
recall function".
•
7
16-time
fl
ash
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 11-5. "Check of R.V. coil".
Replace inverter P.C. board.
•
•
8
'Outdoor unit
stops and
restarts 3
minutes later'
is repeated.
2-time
fl
ash
2.5 seconds OFF
Overcurrent protec-
tion
Large current
fl
ows into power module.
When overcurrent protection occurs within 10 seconds after
compressor starts, compressor restarts after 15 seconds.
Reconnect connector of compressor.
Refer to 11-5. "How to check in-
verter/compressor".
Check stop valve.
•
•
•
9
3-time
fl
ash
2.5 seconds OFF
Discharge tempera-
ture overheat pro-
tection
Temperature of discharge temperature thermistor exceeds
116 °C, compressor stops. Compressor can restart if discharge
temperature thermistor reads 100°C or less 3 minutes later.
Check refrigerant circuit and refrig-
erant amount.
Refer to 11-5. "Check of LEV".
•
•
10
4-time
fl
ash
2.5 seconds OFF
Fin temperature
/P.C. board tem-
perature thermistor
overheat protection
Temperature of
fi
n temperature thermistor on the heat sink
exceeds 80 °C (
HJ25/35
)/75 °C (
HJ50
) or temperature of P.C.
board temperature thermistor on the inverter P.C. board ex-
ceeds 78 °C (
HJ25/35
)/80 °C (
HJ50
).
Check around outdoor unit.
Check outdoor unit air passage.
Refer to 11-5. "Check of outdoor
fan motor".
•
•
•
11
5-time
fl
ash
2.5 seconds OFF
High pressure pro-
tection
Indoor coil thermistor exceeds 70°C in HEAT mode. Defrost
thermistor exceeds 70 °C in COOL mode.
Check refrigerant circuit and refrig-
erant amount.
Check stop valve.
•
•
12
8-time
fl
ash
2.5 seconds OFF
Compressor syn-
chronous abnormal-
ity
The waveform of compressor current is distorted.
Reconnect connector of compressor.
Refer to 11-5. "How to check in-
verter/compressor".
•
•
13
10-time
fl
ash
2.5 seconds OFF
MUZ-HJ50VA
Outdoor fan motor
Outdoor fan has stopped 3 times in a row within 30 seconds
after outdoor fan start-up.
Refer to 11-5. "Check of outdoor
fan motor.
Refer to 11-5. "Check of inverter
P.C. board.
•
•
14
12-time
fl
ash
2.5 seconds OFF
Each phase current
of compressor
Each phase current of compressor cannot be detected nor-
mally.
Refer to 11-5. "How to check in-
verter/compressor".
•
15
13-time
fl
ash
2.5 seconds OFF
DC voltage
DC voltage of inverter cannot be detected normally.
Refer to 11-5. "How to check in-
verter/compressor".
•
16 Outdoor unit
operates.
1-time
fl
ash
2.5 seconds OFF
Frequency drop by
current protection
When the input current exceeds 5.4 A (
HJ25
)/6.1 A (
HJ35
)/
9.2 A (
HJ50
), compressor frequency lowers.
The unit is normal, but check the
following.
Check if indoor
fi
lters are clogged.
Check if refrigerant is short.
Check if indoor/outdoor unit air
circulation is short cycled.
•
•
•
17
3-time
fl
ash
2.5 seconds OFF
Frequency drop by
high pressure pro-
tection
Temperature of indoor coil thermistor exceeds 55 °C in HEAT
mode, compressor frequency lowers.
Frequency drop by
defrosting in COOL
mode
Indoor coil thermistor reads 8 °C or less in COOL mode, com-
pressor frequency lowers.
18
4-time
fl
ash
2.5 seconds OFF
Frequency drop by
discharge tempera-
ture protection
Temperature of discharge temperature thermistor exceeds
111 °C, compressor frequency lowers.
Check refrigerant circuit and refrig-
erant amount.
Refer to 11-5. "Check of LEV".
Refer to 11-5. "Check of outdoor
thermistors".
•
•
•
19
5-time
fl
ash
2.5 seconds OFF
Outside temperature
thermistor protection
When the outside temperature thermistor shorts or opens,
protective operation without that thermistor is performed.
Refer to 11-5. Check of outdoor
thermistors.
•
20
Outdoor unit
operates.
7-time
fl
ash
2.5 seconds OFF
Low discharge tem-
perature protection
Temperature of discharge temperature thermistor has been
50°C or less for 20 minutes.
Refer to 11-5. "Check of LEV".
Check refrigerant circuit and refrig-
erant amount.
•
•
21
8-time
fl
ash
2.5 seconds OFF
PAM protection
PAM: Pulse Ampli-
tude Modulation
The overcurrent
fl
ows into IC821 (Switching power transistor)
(
HJ25/35
)/IC820 (Power module) (
HJ50
) or the bus-bar volt-
age reaches 320 V or more, PAM stops and restarts.
This is not malfunction. PAM pro-
tection will be activated in the fol-
lowing cases:
1 Instantaneous power voltage
drop. (Short time power failure)
2 When the power supply voltage
is high.
22
9-time
fl
ash
2.5 seconds OFF
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
Check if the connector of the com-
pressor is correctly connected.
Refer to 11-5. "How to check
inverter/compressor".
•
NOTE:
1. The location of LED is illustrated at the right
fi
gure. Refer to 11-6.1.
2. LED is lighted during normal operation.
The
fl
ashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the
fl
ashing frequency is “2”.
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
LED
←
Flashing
Inverter P.C. board
MUZ-HJ25/35
LED
←
Flashing
Inverter P.C. board
MUZ-HJ50
OBH648A
