Mitsubishi Electric MSY-D-NA Series, Service Manual

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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
10-3. TROUBLESHOOTING CHECK TABLE
MUZ-D30NA MUZ-D36NA MUY-D30NA MUY-D36NA
No. Symptom
Indication
Abnormal point / Condition Condition Remedy
LED1
(Red) LED2
(Yellow)
1
Outdoor
unit does
not oper-
ate.
Lightning Twice Outdoor power system
IPM protection stop or lock 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 continuously performed 3 times within 3
minutes after start-up.
• Check the connection of the compressor connect-
ing wire.
• Refer to 10-5. "How to check inverter/compres-
sor".
• Refer to 10-5. "Check of compressor start failure".
• Check the stop valve.
2 Lightning 3 times
Discharge temperature therm-
istor
A short circuit is detected in the thermistor during opera-
tion, or an open circuit is detected in the thermistor after 10
minutes of compressor start-up.
• Refer to 10-5. "Check of outdoor thermistors".
3 Lightning 4 times
Fin temperature thermistor
A short or open circuit is detected in the thermistor during
operation.
• Refer to 10-5. "Check of outdoor thermistors".
P.C. board temperature therm-
istor
• Replace the outdoor electronic control P.C. board.
4 Lightning 5 times
Ambient temperature thermis-
tor A short or open circuit is detected in the thermistor during
operation.
• Refer to 10-5. "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 (MUZ)) 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 start-up.
5 Lightning 6 times Serial signal
The communication fails between the indoor and outdoor unit
for 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 con-
tinuously performed twice. • Check the connecting wire between outdoor elec-
tronic 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
continuously performed 10 times.
• Check the connecting wire among outdoor elec-
tronic control P.C. board, noise fi lter P.C. board and
power board.
10
'Outdoor
unit stops
and restarts
3 minutes
later' is
repeated.
Twice Goes out
IPM protection
Overcurrent is detected after 30 seconds of compressor start-
up.
• Reconnect compressor connector.
• Refer to 10-5. "How to check inverter/compres-
sor".
• Refer to 10-5. "Check of compressor start failure".
• 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 temperature protec-
tion
Temperature of discharge temperature thermistor exceeds
241°F (116°C), 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 refrigerant circuit.
• Refer to 10-5. "Check of LEV".
12 4 times Goes out
Fin temperature protection 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 pro-
tection The P.C. board temperature exceeds 158°F (70°C) during
operation.
13 5 times Goes out High-pressure protection
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 around of gas and the refrigerant circuit.
• Check of 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 protection (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 protection (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 protection
A short or open circuit is detected in the current sensor during
compressor operating.
• Replace the power board.
18 Lighting 11 times
Communication between P.C.
boards protection
Communication error occurs between the outdoor electronic
control P.C. board and power board for more than 10 sec-
onds.
• Check the connecting wire between outdoor elec-
tronic 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 elec-
tronic control P.C. board, noise fi lter P.C. board and
power board.
NOTE 1. The location of LED is illustrated at the right figure. Refer to 10-6.1.
2. LED is lighted during normal operation.
Outdoor electronic control P.C. board(Parts side)
Lighting
LED2 LED1
OBH502E