Service manual
44
MUZ-A24NA MUY-A24NA MUZ-GA24NA MUY-GA24NA
No. Symptom
LED indication
Abnormal point /
Condition
Condition Correspondence
LED1(Red)
LED2(Yellow)
1
Outdoor unit
does not oper-
ate.
Lightning
Twice
Outdoor power system
Overcurrent protection stop is continuously performed 3 times
within 1 minute after the compressor gets started, or converter
protection stop or bus-bar voltage protection stop is continu-
ously performed 3 times within 3 minutes after start-up.
• Check the connection of the com-
pressor connecting wire.
• Refer to 10-5.
"How to check in-
verter/compressor".
• Check the stop valve.
2
Lightning
3 times
Discharge temperature
thermistor
A short circuit is detected in the thermistor during operation, or
when an open circuit is detected in the thermistor after 10 min-
utes of compressor start-up.
• Refer to 10-5. "Check of outdoor
thermistor".
3
Lightning
4 times
Fin temperature ther-
mistor
A short or open circuit is detected in the thermistor during op-
eration.
• Refer to 10-5.
"Check of outdoor
thermistor".
• Replace the outdoor electronic
control P.C. board.
4
Lightning
5 times
Ambient temperature
thermistor
A short or open circuit is detected in the thermistor during op-
eration.
• Refer to 10-5. "Check of outdoor
thermistor".
Outdoor heat exchanger
temperature thermistor
A short circuit is detected in the thermistor during operation, or
an open circuit is detected in the thermistor after 5 minutes (in
cooling) and 10 minutes (in heating) of compressor start-up.
Defrost thermistor
(MUZ)
A short circuit is detected in the thermistor during operation, or
an open circuit is detected in the thermistor after 5 minutes of
compressor stat-up.
5
Lightning
6 times
Serial signal The communication fails between the indoor and outdoor unit 3
minutes.
• Refer to 10-5.
"How to check
miswiring and serial signal error.
6
Lightning
7 times
Nonvolatile memory
data
The nonvolatile memory data cannot be read properly. • Replace the outdoor electronic
control P.C. board.
7
Lightning
8 times
Current sensor Current sensor protection stop is continuously performed twice. • Replace the power board.
8
Lightning
11 times
Communication error
between P.C. boards
The communication protection stop between boards is continu-
ously performed twice.
• Check the connecting wire be-
tween outdoor electronic control
P.C. board and power board.
9
Lightning
12 times
Zero cross detecting
circuit
The protection stop of the zero cross detecting circuit is con-
tinuously performed 10 times.
• Check the connecting wire among
outdoor electronic control P.C.
board, noise fi lter P.C. board and
power board.
10
'Outdoor unit
stops and
restarts 3 min-
utes later' is
repeated.
Twice Goes out
lPM protection Overcurrent is detected after 30 minutes of compressor start-
up.
• Reconnect compressor connector.
• Refer to 10-5.
"How to check in-
verter/compressor".
• Check the stop valve.
• Check the power module (PAM
module).
Lock protection Overcurrent is detected within 30 minutes of compressor start-
up.
11 3 times Goes out
Discharge tempera-
ture protection
Discharge temperature exceeds 241°F (116°C) during opera-
tion and compressor stops. Compressor can restart if discharge
temperature thermistor reads 212°F (100°C) or less 3 minutes
later.
• Check the amount of gas and re-
frigerant circuit.
• Refer to 10-5.
"Check of LEV".
12 4 times Goes out
Fin temperature pro-
tection
The fi n temperature exceeds 189°F (87°C) during operation. • Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 10-5. "Check of outdoor
fan motor".
P.C. board temperature
protection
The P.C. board temperature exceeds 158°F (70°C) during op-
eration.
13 5 times Goes out
High-Pressure pro-
tection
The outdoor heat exchanger temperature exceeds 158°F (70°
C) during cooling or indoor gas pipe temperature exceeds 158°
F (70°C) during heating (MUZ).
• Check the amount of gas and the
refrigerant circuit.
• Check the stop valve.
14 8 times Goes out
Converter protection A failure is detected in the operation of the converter during op-
eration.
• Replace the power board.
15 9 times Goes out
Bus-bar voltage pro-
tection (1)
The bus-bar voltage exceeds 400 V or falls to 200 V or below
during compressor operating.
• Check the voltage of power supply.
• Replace the power board or the
outdoor electronic control P.C.
board.
• Refer to 10-5. "Check of bus-bar
voltage".
Bus-bar voltage pro-
tection (2)
The bus-bar voltage exceeds 400 V or falls to 50 V or below
during compressor operating.
16 13 times Goes out
Outdoor fan motor Failure occurs continuously three times within 30 seconds after
the fan gets started.
• Refer to 10-5. "Check of outdoor
fan motor".
17 Lighting 8 times
Current sensor pro-
tection
A short or open circuit is detected in the current sensor during
compressor operating.
• Replace the power board.
18 Lighting 11 times
Communication be-
tween P.C. boards
protection
Communication error occurs between the outdoor electronic
control P.C. board and power board for more than 10 seconds
• Check the connecting wire be-
tween outdoor electronic control
P.C. board and power board.
19 Lighting 12 times
Zero cross detecting
circuit protection
Zero cross signal cannot be detected while the compressor is
operating.
• Check the connecting wire among
outdoor electronic control P.C.
board, noise fi lter P.C. board and
power board.
NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 10-6.3.
2. LED is lighted during normal operation.
The fl ashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the fl ashing frequency is “2”.
Outdoor electronic control P.C. board(Parts side)
Lighting
LED2
LED1
The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the flashing frequency is “2”.
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON