Mitsubishi Electric TRANE NTXFKS09A112AA Service Manual page 26

9-4. 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
Indoor coil
Left lamp blinks.
thermistor
2-time blink
2
Room
tempera-
2.5-second OFF
ture
thermistor
Left lamp blinks.
3-time blink
Indoor fan
3
motor
2.5-second OFF
Left lamp blinks.
Indoor
4-time blink
4
control
system
2.5-second OFF
Left lamp blinks.
5-time blink
Outdoor
5 power
system
Left lamp blinks.
6-time blink
Outdoor
6
thermistors
Left lamp blinks.
7-time blink
Outdoor
7 control
system
Left lamp blinks.
14-time blink or more
Other
8
abnormality
2.5-second OFF
Outdoor
control
9
Left lamp lights up
system
OBHT752
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.
Condition
The serial signal from the outdoor unit is not
received for a maximum of 6 minutes.
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
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
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.
26
Remedy
• Refer to 9-6. "How to check
miswiring and serial signal
error".
• Refer to the characteristics of
indoor coil thermistor, and the
room temperature thermistor
on 9-7.
• Refer to 9-6. "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.