Indoor Unit - Mitsubishi Electric SUZ-M-VA Series Service Manual

11-4. 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 blinks.
OPERATION INDICATOR
Abnormal
No.
Operation indicator lamp
point
Left lamp blinks.
0.5-second ON
Miswiring
1 or serial
signal
0.5-second OFF
Left lamp blinks.
Indoor coil
2-time blink
thermistor
2
Room
2.5-second OFF
tempera-
ture
thermistor
Left lamp blinks.
3-time blink
3 Indoor fan
motor
2.5-second OFF
Left lamp blinks.
4-time blink
Indoor
4 control
system
2.5-second OFF
Left lamp blinks.
Outdoor
5-time blink
5
power
system
Left lamp blinks.
6-time blink
Outdoor
6
thermistors
Left lamp blinks.
Outdoor
7-time blink
control
7
system
Left lamp blinks.
14-time blink or more
Other
abnormali
8
ty
2.5-second OFF
Outdoor
Left lamp lights up
control
9
system
Left lamp blinks 3 times, then
right lamp lights on.
Left lamp
Refrigerant
leakage
10
(Sensor
Right lamp
detection)
Left lamp blinks 2 times, then
right lamp lights on.
Left lamp
Refrigerant
11
sensor
Right lamp
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 11-2.1. 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 blink as shown in No.1
after the procedure, refer to 11-6.
OBH843
Lit
Blinking
Not lit
Symptom
Indoor unit and
outdoor unit do
not operate.
Indoor unit and
outdoor unit do
not operate.
Indoor unit and
outdoor unit do
not operate.
Indoor unit and
outdoor unit do
not operate.
Indoor unit and
outdoor unit do
not operate.
2.5-second OFF
Indoor unit and
outdoor unit do
not operate.
2.5-second OFF
Indoor unit and
outdoor unit do
not operate.
2.5-second OFF
Indoor unit and
outdoor unit do
not operate.
Outdoor unit
does not
operate.
•FAN operation
starts, and the
air blows
upward from
the horizontal
3.0-second OFF
vane.
•It cannot be
controlled by
3.0-second ON
the remote
controller.
•Indoor unit and
outdoor unit
do not
operate.
3.0-second OFF
3.0-second ON
"How to check miswiring and serial error".
Condition
The serial signal from the outdoor unit is not
received for a maximum of 6 minutes.
The indoor unit is connected to a
low-standby-power model after once connected
to a non-low-standby-power model.
The indoor coil or the room temperature
thermistor 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
compressor stops for overcurrent protection or
startup failure protection within 1 minute after
startup.
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
outdoor 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
outdoor electronic control P.C. board.
Refrigerant leaks from the piping or the heat
exchanger in the indoor unit.
The following items are used around the

indoor unit.

• Spray (LP gas including Freon, and whose
main ingredient is propane and butane)
• Aerosol insecticide (including ethanol)
• Air spray painting (including dichloromethane)
• Charcoal (charcoal fire)
• Chemicals (such as ethanol)
The refrigerant sensor mounted on the indoor
unit does not work .
The refrigerant sensor is not connected
properly or the wire is broken.
29
Remedy
• Refer to 11-6. "How to check
miswiring and serial signal
error".
• Refer to NOTE.
• Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
on 11-7.
• Refer to 11-6. "Check of
indoor fan motor".
• Replace the indoor electronic
control P.C. board.
• Refer to "Check of inverter/
compressor".
• Refer to the outdoor unit
service manual.
• Check the stop valve.
• Refer to "Check of outdoor
thermistor".
• Refer to the outdoor unit
service manual.
• Replace the inverter P.C.
board or the outdoor electronic
control P.C. board.
Refer to the outdoor unit
service manual.
• Check the stop valve.
• Check the 4-way valve.
• Check the abnormality in
detail using the failure mode
recall function.
Refer to the outdoor unit
service manual.
• Check the blinking pattern of
the LED on the inverter P.C.
board or the outdoor electronic
control P.C. board.
• Turn off the power after FAN
operation is finished. (FAN
operation continues for 3
hours.)
• Check the indoor unit to detect
the part where refrigerant leaks.
• Repair the part where
refrigerant leaks.
• Turn on the power again.
• Replace the refrigerant sensor
if the problem is not fixed.
Connect the connector of the
refrigerant sensor properly.
Replace the refrigerant sensor.