Mitsubishi Electric MSH-GA60VB-E1 Service Manual page 14

9-3. Troubleshooting check table
• The following indication applies regardless of shape of the indicator.
Operation Indicator
· Flashing of the OPERATION INDICATOR lamp (on the left-hand side) indicates possible
abnormalities.
· The OPERATION INDICATOR lamp (on the left-hand side) is lighting during normal operation.
Before taking measures, make sure that the symptom reappears for accurate troubleshooting.
Self check table
Abnormal
No. Operation indicator lamp
point
0.5-second ON
1 Mis-Wiring
0.5-second OFF
Indoor coil
2-time flash
thermistor
2
Room
temperature
2.5-second OFF
thermistor
3-time flash
Indoor fan
3
motor
2.5-second OFF
4-time flash
Indoor
control
4
system
2.5-second OFF
6-time flash
Outdoor
5
thermistor
7-time flash
Outdoor
control
6
system
10-time flash
MUH-GA80VB
Low
discharge
7
temperature
protection
2.5-second OFF
NOTE : When the indoor unit has started operation and the above detection method has detected an abnormality (the first
detection after the power ON), the indoor electronic control P.C. board turns OFF the indoor fan motor with the
OPERATION INDICATOR lamp flashing.
OB367D
Lighted
Not lighted
Symptom
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Indoor fan repeats
12 seconds ON
and 3minutes OFF.
When the indoor
fan breaks, the fan
keeps stopping.
Outdoor unit
does not
operate.
Outdoor unit
does not
2.5-second OFF operate.
Outdoor unit
does not
operate.
2.5-second OFF
Outdoor unit
does not
operate.
Condition
3 minutes after power supply turns ON, when
serial signal is not received.
Detect Indoor coil/room temperature
thermistor short or open circuit every 8
seconds during operation.
Rotational frequency feedback signal is not
emitted for 12-second after indoor fan motor is
operated.
It cannot properly read data in the nonvolatile
memory of the indoor electronic control P.C.
board.
<Thermistor short>
Thermistors are abnormal when they short
after compressor start-up.
<Thermistor open>
Thermistors are abnormal when they open
after compressor start-up.
However, discharge temperature thermistor is
abnormal when open circuit is detected more
than 10 minutes after compressor start-up.
It cannot properly read data in the nonvolatile
memory of the deicer P.C. board.
Outdoor unit stops [and restarts 3 minutes
later (MUH-GA60VB).]
MUH-GA80VB
Discharge temperature has been 50: or less
on cool operation, or has been 49: or less on
heat operation for 20 minutes.
14
Remedy
• Refer to 9-5. D "How to check
mis-wiring ".
• Refer to the characteristics
of indoor coil thermistor, and
room temperature thermistor
(9-6.).
• Refer to 9-5. A "Check of
indoor fan motor".
• Check the indoor electronic
control P.C. board.
• Shortage of refrigerant
• Check the deicer P.C.
board.
Refer to "Check of outdoor
thermistor". Refer to outdoor
service manual.
• Check the deicer P.C. board.
Refer to outdoor service
manual.
MUH-GA80VB
• Refer to "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
Refer to outdoor unit service
manual.