Mitsubishi Electric MUZ-GL09NA Service Manual page 46

10-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication
Outdoor unit 1-time blink every
does not op- 2.5 seconds
erate.
1
2
3
6-time blink
4
2.5 seconds OFF
11-time blink
5
2.5 seconds OFF
16-time blink
2.5 seconds OFF
6
17-time blink
2.5 seconds OFF
7
'Outdoor unit 2-time blink
stops and 2.5 seconds OFF
8
restarts 3
minutes later'
is repeated.
3-time blink
2.5 seconds OFF
9
4-time blink
2.5 seconds OFF
10
5-time blink
2.5 seconds OFF
11
8-time blink
2.5 seconds OFF
12
10-time blink
2.5 seconds OFF
13
12-time blink
14
2.5 seconds OFF
13-time blink
2.5 seconds OFF
15
NOTE:
2. LED is lit during normal operation.
3. Blinking patterns of this mode differ from the ones of the failure recall mode.
The blinking frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the blinking frequency is "2".
ON
2.5-second OFF
OFF
OBH733G
Abnormal point/
Condition
Outdoor power sys- Overcurrent protection cut-out operates 3 consecutive times
tem within 1 minute after the compressor gets started.
Outdoor thermistors
defrost thermistor, P.C. board temperature thermistor, outdoor
heat exchanger temperature thermistor or ambient tempera-
ture thermistor shorts or opens during compressor running.
Outdoor control sys- Nonvolatile memory data cannot be read properly.
tem
(The upper lamp of the OPERATION INDICATOR lamp on the
indoor unit lights up or blinks 7-time.)
Serial signal The communication fails between the indoor and outdoor unit
for 3 minutes.
Stop valve/ Closed valve is detected by compressor current.
Closed valve
4-way valve/ The 4-way valve does not work properly.
Pipe temperature The indoor coil thermistor detects an abnormal temperature.
Outdoor refrigerant A closed valve and air trapped in the refrigerant circuit are
system abnormality detected based on the temperature sensed by the indoor and
outdoor thermistors and the current of the compressor.
Overcurrent protec-
tion GL09/12/15/18, MUY-GL09/12/15/18)/ IGBT module (IC700)
(MUZ-GL24, MUY-GL24).
Discharge tem- Temperature of discharge temperature thermistor exceeds
perature overheat 241°F (116°C), compressor stops. Compressor can restart if
protection discharge temperature thermistor reads 212°F (100°C) or less
3 minutes later.
Fin temperature
/P.C. board tem- exceeds 167 - 187°F (75 - 86°C) (MUZ-GL09/12/15/18, MUY-
perature thermistor GL09/12/15/18)/167 - 176°F (75 - 80°C) (MUZ-GL24, MUY-
overheat protection GL24) or temperature of P.C. board temperature thermistor on
the inverter P.C.board exceeds 162 - 185°F (72 - 85°C) (MUZ-
GL09/12/15/18, MUY-GL09/12/15/18)/158 - 167°F (70 - 75°C)
(MUZ-GL24, MUY-GL24).
High pressure pro- Indoor coil thermistor exceeds 158°F (70°C) in HEAT mode.
tection Defrost thermistor exceeds 158°F (70°C) in COOL mode.
Compressor syn- The waveform of compressor current is distorted.
chronous abnormal-
ity
Outdoor fan motor Outdoor fan has stopped 3 times in a row within 30 seconds
after outdoor fan startup.
Each phase current
Each phase current of compressor cannot be detected nor-
of compressor
mally.
Bus-bar voltage (DC) Bus-bar voltage of inverter cannot be detected normally.
0.5-second ON
2.5-second OFF
Condition
MUZ-
Inverter P.C. board
MUZ-GL09/12/15/18NA(H)
MUY-GL09/12/15/18NA
0.5-second ON
46
Remedy
• Reconnect connector of compres-
sor.
• Refer to 10-5. "How to check
inverter/compressor".
• Check stop valve.
• Refer to 10-5. "Check of outdoor
thermistors".
• Replace inverter P.C. board.
• Refer to 10-5. "How to check
miswiring and serial signal error.
• Check stop valve.
• Refer to 10-5. "Check of R.V.
coil".
• Replace the inverter P.C. board.
• Check for a gas leak in a
connecting piping etc.
• Check the stop valve.
• Refer to 10-5. "Check of outdoor
refrigerant circuit".
• Reconnect connector of compressor.
• Refer to 10-5. "How to check
inverter/compressor".
• Check stop valve.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 10-5. "Check of outdoor
fan motor".
• Check refrigerant circuit and refrig-
erant amount.
• Check stop valve.
• Reconnect connector of compressor.
• Refer to 10-5. "How to check
inverter/compressor".
• Refer to 10-5. "Check of outdoor
fan motor.
• Refer to 10-5. "Check of inverter
P.C. board.
• Refer to 10-5. "How to check
inverter/compressor".
• It occurs with following case.
Instantaneous power voltage drop.
(Short time power failure) (MUZ-
GL24, MUY-GL24)
• Refer to 10-5. "Check of power
supply". (MUZ-GL24, MUY-GL24)
• Refer to 10-5. "How to check in-
verter/compressor".
MUZ-GL24NA(H)
MUY-GL24NA
Blinking
LED
LED