Mitsubishi Electric MSZ-G09SV Service Manual page 70

INDOOR UNIT
MSZ-G20SV -
E1
•The following indication applies regardless of shape of the indicator.
flashing
Operation Indicator
NOTE: 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
tempera- 2.5-second OFF
ture
thermistor
3-time flash
Indoor fan
3
motor
2.5-second OFF
4-time flash
Indoor
control
4
system
2.5-second OFF
5-time flash
Outdoor
power
5
system
6-time flash
Outdoor
6
thermistors
7-time flash
Outdoor
control
7
system
10-time flash
Low
discharge
8
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.
· 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.
Symptom
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
Indoor fan
repeats 12
seconds ON
and 3
minutes
OFF.
When the
indoor fan
breaks, the
fan keeps
stopping.
Outdoor unit
does not
operate.
Outdoor unit
does not
operate.
2.5-second OFF
Outdoor unit
does not
operate.
2.5-second OFF
Outdoor unit
does not
operate.
2.5-second OFF
Outdoor unit
does not
operate.
Detection method
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.
When rotational frequency feedback signal is
not emit during 12-second indoor fan
operation.
When it cannot properly read data in the
nonvolatile memory of indoor electronic
control P.C. board.
When compressor has stopped due to over
current protection or start-up failure protection
3 times in a row within 5 seconds after start-
up.
<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.
When it cannot properly read data in the
nonvolatile memory of outdoor electronic
control P.C. board.
When discharge temperature has been 50:
or less on cool operation, or is 49: or less on
heat operation for 20 minutes.
70
Checkpoint
• Refer to V "How to check
mis-wiring " on page 86.
• Refer to the characteristics of
indoor coil thermistor,
sub indoor coil
thermistor, and room
temperature thermistor on
page 91.
• Refer to R "Check of
indoor fan motor" on page 84.
• Replace the indoor electronic
control P.C. board.
• Refer to Y "Check of inverter/
compressor" on page 88.
• Shortage of refrigerant
• Replace the outdoor control
P.C. board.
Refer to Z "Check of outdoor
thermistor" on page 89.
• Replace the outdoor
electronic control P.C. board.
• Refer to W,X or
.
AA
Check refrigerant system
related items on page 87, 88
or 89.
• Check refrigerant circuit and
refrigerant amount.