Mitsubishi Electric MUZ-GB50VA, Service Manual

Page: 23 / 52

23
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
11-3. TROUBLESHOOTING CHECK TABLE
MUZ-GB50VA-
E1
/
E2
No. Symptom
LED indication
Abnormal point/ Con-
dition
Condition Remedy
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 when
converter protection stop or bus-bar voltage protection stop is
continuously performed three times within 3 minutes after start-
up.
• Check the connection of the com-
pressor connecting wire.
• Refer to 11-5. "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 11-5. "Check of outdoor
thermistors".
3 Lightning 4 times
Fin temperature
thermistor
A short or open circuit is detected in the thermistor during op-
eration.
• Refer to 11-5. "Check of outdoor
thermistors".
P.C. board tempera-
ture 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 11-5. "Check of outdoor
thermistors".
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 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 11-5. "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 seconds of compressor start-
up.
• Reconnect compressor connector.
• Refer to 11-5. "How to check in-
verter/compressor".
• Check the stop valve.
• Check the power module (PAM
module).
Lock protection Overcurrent is detected within 30 seconds of compressor start-
up.
11 3 times Goes out
Discharge tempera-
ture protection
Discharge temperature exceeds 116°C during operation and
compressor stops. Compressor can restart if discharge tem-
perature thermistor reads 100°C or less 3 minutes later.
• Check the amount of gas and re-
frigerant circuit.
• Refer to 11-5. "Check of LEV".
12 4 times Goes out
Fin temperature pro-
tection
The fi n temperature exceeds 87°C during operation. • Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 11-5. "Check of outdoor
fan motor".
P.C. board temperature
protection
The P.C. board temperature exceeds 70°C during operation.
13 5 times Goes out
High-Pressure pro-
tection
The outdoor heat exchanger temperature exceeds 70°C during
cooling or indoor gas pipe temperature exceeds 70°C during
heating.
• 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
operation.
• 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 out-
door electronic control P.C. board.
• Refer to 11-5. "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 11-5. "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 10-6.1.
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