Mitsubishi Electric MUZ-HE09NA, Service Manual, Page: 34 / 62

34
3. Outdoor unit failure mode table
OPERATION
INDICATOR
upper lamp
(Indoor unit)
Abnormal point
(Failure mode / protection)
LED indication
(Outdoor P.C. board)
Condition Remedy
Indoor/
outdoor unit
failure mode
recall function
Outdoor unit
failure mode
recall function
OFF None (Normal) — — — — —
2-time fl ash
2.5 seconds
OFF
Outdoor power system
—
Overcurrent protection cut-out operates
3 consecutive times within 1 minute
after the compressor gets started.
Reconnect connectors.
Refer to 10-5. "How
to check inverter/
compressor".
Check the stop valve.
•
•
•
○ ○
3-time fl ash
2.5 seconds
OFF
Discharge temperature
thermistor
1-time fl ash every
2.5 seconds
Thermistor shorts or opens during
compressor running.
Refer to 10-5. "Check
of outdoor thermistors".
Defective outdoor
thermistors can be
identi fi ed by checking
the blinking pattern of
LED.
•
○ ○
Defrost thermistor
Fin temperature thermistor 3-time fl ash
2.5 seconds OFF
P.C. board temperature
thermistor
4-time fl ash
2.5 seconds OFF
Ambient temperature
thermistor
2-time fl ash
2.5 seconds OFF
Outdoor heat exchanger
temperature thermistor
(MUZ-HE24)
4-time fl ash
2.5 seconds
OFF
Overcurrent 11-time fl ash
2.5 seconds OFF
Large current fl ows into intelligent
power module/ power module 1.
Reconnect compressor
connector.
Refer to 10-5. "How
to check inverter/
compressor".
Check the stop valve.
•
•
•
—
○
Compressor synchronous
abnormality (Compressor start-
up failure protection)
12-time fl ash
2.5 seconds OFF
Waveform of compressor current is
distorted.
Reconnect compressor
connector.
Refer to 10-5. "How
to check inverter/
compressor".
•
•
—
○
5-time fl ash
2.5 seconds
OFF
Discharge temperature
—
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 refrigerant
circuit and the
refrigerant amount.
Refer to 10-5. "Check
of LEV".
•
•
—
○
6-time fl ash
2.5 seconds
OFF
High pressure
—
Temperature of indoor coil thermistor
exceeds 158°F (70°C) in HEAT mode.
Temperature of outdoor heat exchanger
temperature thermistor exceeds 158°F
(70°C) in COOL mode.
Check the refrigerant
circuit and the
refrigerant amount.
Check the stop valve.
•
•
—
○
7-time fl ash
2.5 seconds
OFF
Fin temperature/ P.C. board
temperature
7-time fl ash
2.5 seconds OFF
Temperature of fi n temperature
thermistor on the inverter P.C. board
exceeds 167 ~ 176°F (75 ~ 80°C), or
temperature of P.C. board temperature
thermistor on the inverter P.C. board
exceeds 158 ~ 167°F (70 ~ 75°C).
Check around the
outdoor unit.
Check the outdoor unit
air passage.
Refer to 10-5. "Check
of outdoor fan motor".
•
•
•
—
○
8-time fl ash
2.5 seconds
OFF
Outdoor fan motor
—
Outdoor fan has stopped 3 times in a
row within 30 seconds after outdoor fan
start-up.
Refer to 10-5. "Check
of outdoor fan motor".
Refer to 10-5. "Check
of inverter P.C. board".
•
—
○
9-time fl ash
2.5 seconds
OFF
Nonvolatile memory data 5-time fl ash
2.5 seconds OFF
Nonvolatile memory data cannot be
read properly.
Replace the inverter
P.C. board.
•
○ ○
Power module
(MUZ-HE24NA)
6-time fl ash
2.5 seconds OFF
The interphase short circuit occurs
in the output of the intelligent power
module (IPM)/power module (IPM) 1.
The compressor winding shorts circuit.
Refer to 10-5. "How
to check inverter/
compressor".
•
10-time fl ash
2.5 seconds
OFF
Discharge temperature
—
Temperature of discharge temperature
thermistor has been 122°F (50°C) or
less for 20 minutes.
Refer to 10-5. "Check
of LEV".
Check the refrigerant
circuit and the
refrigerant amount.
•
•
—
○
NOTE : Blinking patterns of this mode differ from the ones of Troubleshooting check table (10-3.).
1
Intelligent power module: MUZ-HE24NA
Power module: Other models
OBH686