24
ON
OFF
2.5-second OFF
2.5-second OFF
NOTE 1. The location of LED is illustrated at the right figure. Refer to page 32.
2. LED lights up during normal operation.
The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the flashing frequency is “2”.
Abnormal point/ Condition
When compressor has stopped by overcurrent protection within
1 minute 3 times in a row after compressor start-up, unit stops.
When discharge temperature thermistor, fin temperature
thermistor or defrost thermistor shorts or opens during
compressor running, compressor stops and restarts 3 minutes
later.
When nonvolatile memory data cannot be read properly,
compressor stops and restarts 3 minutes later.
When 12A(MUZ-A09YV, MUZ-A09YVH)/ 20A(MUZ-A12YV,
MUZ-A12YVH) current flows into power transistor module,
compressor stops and restarts 3 minutes later.
When discharge temperature thermistor exceeds 116
:
,
compressor stops. Compressor can restart if discharge
temperature thermistor reads 100
:
or less 3 minutes later.
When temperature at heat sink exceeds 83
:
or temperature of
inverter P.C. board exceeds 79
:
, compressor stops and
restarts 3 minutes later.
When indoor coil thermistor exceeds 70
:
.
When the defrost thermistor exceeds 70
:
in COOL mode.
When current from power outlet exceeds 7A(MUZ-A09YV,
MUZ-A09YVH)/ 9A(MUZ-A12YV, MUZ-A12YVH), compressor
frequency lowers.
When indoor coil thermistor exceeds 55
:
in HEAT mode,
compressor frequency lowers.
When indoor coil thermistor reads 6
:
or less in COOL mode,
compressor frequency lowers.
When discharge temperature thermistor exceeds 110
:
,
compressor frequency lowers.
When discharge temperature has been 40
:
or less for 20
minutes.
No.
1
2
3
5
6
7
8
10
11
12
14
15
Symptom
LED indication
Detection method
Checkpoint
Outdoor unit
does not
operate
'Outdoor unit
stops and
restarts 3
minutes later'
is repeated
Outdoor unit
operates (at
low
frequency)
Outdoor unit
operates
1-time flash every
2.5 seconds
NOTE:
For abnormality
location, refer to
'Indoor
troubleshooting
check table'.
Refer to service
manual OB327.
2-time flash
2.5 seconds OFF
3-time flash
2.5 seconds OFF
4-time flash
2.5 seconds OFF
5-time flash
2.5 seconds OFF
1-time flash
2.5 seconds OFF
3-time flash
2.5 seconds OFF
4-time flash
2.5 seconds OFF
7-time flash
2.5 seconds OFF
Outdoor power
system
Outdoor
thermistors
Outdoor control
system
Overcurrent
protection
Discharge
temperature
overheat
protection
Fin temperature
thermistor overheat
protection
High pressure
protection
Frequency drop by
current protection
Frequency drop by
high pressure
protection
Frequency drop by
defrosting in COOL
mode
Frequency drop by
discharge
temperature
protection
Low discharge
temperature
protection
· Check stop valve.
· Reconnect connectors.
· Refer to
A
"How to check inverter/
compressor" on page 26.
· Refer to
G
"Check of outdoor
thermistors" on page 28.
· Check stop valve.
· Reconnect connectors.
· Refer to
A
"How to check inverter/
compressor" on page 26.
Replace inverter P.C. board after
check of
A
"How to check inverter/
compressor" on page 26 and
G
"Check of outdoor thermistors" on
page 28.
· Check refrigerant circuit and
refrigerant amount.
· Refer to
G
"Check of outdoor
thermistors" on page 28.
· Refer to
L
"Check of LEV" on page
30.
· Check around outdoor unit.
· Check outdoor unit air passage.
· Refer to
I
"Check of outdoor fan
motor" on page 29.
· Check refrigerant circuit and
refrigerant amount.
· Check stop valve.
The unit is normal, but check the
following.
· Check if indoor filters are clogged.
· Check if refrigerant is short.
· Check if indoor/outdoor unit air
circulation is short cycled.
· Refer to
L
"Check of LEV" on
page 30.
· Check refrigerant circuit and
refrigerant amount.
<Inverter P.C. board>
LED
Flashing
Refer to
A
"How to check inverter/
compressor" on page 26.
When the bus-bar voltage of inverter cannot be detected
normally.
Bus-bar voltage
8-time flash
2.5 seconds OFF
Compressor
sinusoidal current
When the waveform of compressor current is distorted.
· Check stop valve.
· Reconnect connector.
· Refer to
A
"How to check inverter/
compressor" on page 26.
8-time flash
2.5 seconds OFF
PAM protection
PAM:
Pulse
Amplitude
Modulation
When the overcurrent flows into IGBT(Insulated Gate Bipolar
transistor : TR821) or when the bus-bar voltage reaches 300V
or more, PAM stops and restarts.
This is not malfunction.
PAM protection will be activated in
the following cases;
1
Instantaneous power voltage drop
(Short time power failure)
2
When the power supply voltage is
high.
9-time flash
2.5 seconds OFF
Inverter check
mode
When the connector of compressor is disconnected, inverter
check mode starts.
Check if the connector is correctly
connected.
Refer to
A
"How to check inverter/
compressor" on page 26.
4
9
16
13
When ambient temperature thermistor shorts or opens during
compressor running.
5-time flash
2.5 seconds OFF
Outdoor
thermistors
· Refer to
G
"Check of outdoor
thermistors" on page 28.
0.5-second ON
0.5-second ON
1. Troubleshooting check table
OB328 A--1qxp 04.4.26 4:49 PM Page 24
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