Mitsubishi Electric MSZ-SF25VE Service Manual page 22

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.
OPERATION INDICATOR
Abnormal
No. Operation indicator lamp
point
Left lamp fl ashes.
0.5-second ON
Miswiring
1 or serial
signal
0.5-second OFF
Left lamp fl ashes.
Indoor coil
2-time fl ash
thermistor
2
Room tem-
perature 2.5-second OFF
thermistor
Left lamp fl ashes.
3-time fl ash
Indoor fan
3
motor
2.5-second OFF
Left lamp fl ashes.
4-time fl ash
Indoor con-
4
trol system
Left lamp fl ashes.
5-time fl ash
Outdoor
5 power sys-
tem
Left lamp fl ashes.
6-time fl ash
Outdoor
6
thermistors
Left lamp fl ashes.
7-time fl ash
Outdoor
7 control sys-
tem
Left lamp fl ashes.
14-time fl ash or more
Other ab-
8
normality
2.5-second OFF
Outdoor
9 control sys- Left lamp lights up
tem
NOTE: The indoor unit may have been connected to a non-low-standby-power model outdoor unit. To use a low-standby-power
model, clear the error history by referring to "Deleting the memorized abnormal condition" described in 10-2.1. When the
error history is being cleared, the connection information also will be initialized. The indoor unit will be compatible with a
low-standby-power model after initialization. If the operation indicator lamp continues to fl ash as shown in No.1 after the
procedure, refer to 10-6.
OBH600B
Lighted
Blinking
Not lighted
2.5-second OFF
Indoor unit and
outdoor unit do
not operate.
2.5-second OFF
2.5-second OFF
2.5-second OFF
Outdoor unit
does not oper-
ate
"How to check miswiring and serial error".
Symptom Condition
The serial signal from the outdoor unit is not
received for 6 minutes.
The indoor unit is connected to a low-stand-
by-power model after once connected to a
non-low-standby-power model.
The indoor coil or the room temperature ther-
mistor is short or open circuit.
The rotational frequency feedback signal is
not emitted during the indoor fan operation.
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
It consecutively occurs 3 times that the com-
pressor stops for overcurrent protection or
start-up failure protection within 1 minute after
start-up.
The outdoor thermistors short or open circuit
during the compressor operation.
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
An abnormality other than above mentioned
is detected.
It cannot properly read data in the nonvolatile
memory of the inverter P.C. board or the out-
door electronic control P.C. board.
22
Remedy
• Refer to 10-6. "How to check
miswiring and serial signal er-
ror".
• Refer to NOTE.
• Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
(10-7.).
• Refer to 10-6. "Check of in-
door fan motor".
• Replace the indoor electronic
control P.C. board.
• Refer to "How to check of in-
verter/compressor".
Refer to outdoor unit service
manual
• Check the stop valve.
• Refer to "Check of outdoor
thermistor".
Refer to outdoor unit service
manual.
• Replace the inverter P.C. board
or the outdoor electronic control
P.C. board.
Refer to outdoor unit service
manual.
• Check the stop valve.
• Check the 4-way valve.
• Confi rm the abnormality in
detail using the failure mode
recall function for outdoor unit.
• Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.