20
10-4. TROUBLESHOOTING CHECK TABLE
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
When the indoor unit has started operation and detected an abnormality of the following condition (the first detection after
the power ON), the indoor fan motor turns OFF and OPERATION INDICATOR lamp flashes.
No. Abnormal
point
Operation indicator lamp
Symptom
Condition
Remedy
1
Miswiring
or serial
signal
Upper lamp
fl
ashes.
0.5-second ON
0.5-second OFF
Indoor unit and
outdoor unit do
not operate.
The serial signal from the outdoor unit is not
received for 6 minutes.
• Refer to 10-6. "How to check
miswiring and serial signal er-
ror".
2
Indoor coil
thermistor
Upper lamp
fl
ashes.
2-time
fl
ash
2.5-second OFF
The indoor coil or the room temperature ther-
mistor is short or open circuit.
• Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
(10-7.).
Room tem-
perature
thermistor
3
Indoor fan
motor
Upper lamp
fl
ashes.
3-time
fl
ash
2.5-second OFF
The rotational frequency feedback signal is
not emitted during the indoor fan operation.
• Refer to 10-6. "Check of
indoor fan motor".
4
Indoor con-
trol system
Upper lamp
fl
ashes.
4-time
fl
ash
2.5-second OFF
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
• Replace the indoor electronic
control P.C. board.
5
Outdoor
power sys-
tem
Upper lamp
fl
ashes.
5-time
fl
ash
2.5-second OFF
It consecutively occurs 3 times that the com-
pressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.
• Refer to "How to check of in-
verter/compressor".
Refer to outdoor unit service
manual
• Check the stop valve.
6
Outdoor
thermistors
Upper lamp
fl
ashes.
6-time
fl
ash
2.5-second OFF
The outdoor thermistors short or open circuit
during the compressor operation.
• Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
7
Outdoor
control sys-
tem
Upper lamp
fl
ashes.
7-time
fl
ash
2.5-second OFF
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
• Replace the inverter P.C. board
or the outdoor electronic con-
trol P.C. board.
Refer to outdoor unit service
manual.
8
Other ab-
normality
Upper lamp
fl
ashes.
14-time
fl
ash or more
2.5-second OFF
An abnormality other than above mentioned
is detected.
• Check the stop valve.
• Check the 4-way valve.
• Con
fi
rm the abnormality in
detail using the failure mode
recall function for outdoor unit.
9
Outdoor
control sys-
tem
Upper lamp lights up
Outdoor unit
does not oper-
ate
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
• Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.
OPERATION INDICATOR
Lighted
Blinking
Not lighted
OBH750
