27
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
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.
7
17-time
fl
ash
2.5 seconds OFF
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 11-5. “Check of outdoor
refrigerant circuit”.
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 or temperature of P.C. board temperature ther-
mistor on the inverter P.C. board exceeds 78°C.
• 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
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".
14
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".
15 Outdoor unit
operates.
1-time
fl
ash
2.5 seconds OFF
Frequency drop by
current protection
When the input current exceeds 5.4 A (
DM25
)/6.1 A (
DM35
),
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.
16
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.
17
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".
18
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.
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
OBH751
