Mitsubishi Electric MUZ-HE09NA, Service Manual

Page: 36 / 62

36
10-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication
Abnormal point/
Condition
Condition Remedy
1
Outdoor
unit does
not oper-
ate.
1-time fl ash every
2.5 seconds
Outdoor power sys-
tem
Overcurrent protection cut-out operates 3 consecutive times with-
in 1 minute after the compressor gets started, or failure of restart
of compressor has repeated 24 times.
Reconnect connector of compressor.
Refer to 10-5. "How to check inverter/
compressor".
Check the stop valve.
•
•
•
2
Outdoor thermistors Discharge temperature thermistor, fi n temperature thermistor, de-
frost thermistor, outdoor heat exchanger temperature thermistor,
P.C. board temperature thermistor or ambient temperature therm-
istor shorts or opens during compressor running.
Refer to 10-5. "Check of outdoor
thermistors".
•
3
Outdoor control sys-
tem
Nonvolatile memory data cannot be read properly.
(The upper lamp of OPERATION INDICATOR of the indoor unit
lights up or fl ashes 7 times.)
Replace inverter P.C. board. •
4
6-time fl ash
2.5 seconds OFF
Serial signal The communication fails between the indoor and outdoor unit for
3 minutes.
Refer to 10-5. "How to check miswir-
ing and serial signal error.
•
5
11-time fl ash
2.5 seconds OFF
Stop valve/
Closed valve
Closed valve is detected by compressor current. Check the stop valve. •
6
14-time fl ash
2.5 seconds OFF
Outdoor unit
(Other abnormality)
Outdoor unit is defective. Refer to 10-2.2. "Flow chart of the de-
tailed outdoor unit failure mode recall
function".
•
7
16-time fl ash
2.5 seconds OFF
4-way valve/
Pipe temperature
The 4-way valve does not work properly.
The indoor coil thermistor detects an abnormal temperature.
Refer to 10-5. "Check of R.V. coil".
Replace the inverter P.C. board.
•
•
8
'Outdoor
unit stops
and re-
starts 3
minutes
later' is
repeated.
2-time fl ash
2.5 seconds OFF
Overcurrent protec-
tion
Large current fl ows into intelligent power module/power module
1.
When overcurrent protection occurs within 10 seconds after
compressor starts, compressor restarts after 15 seconds
(MUZ-HE09/12/15/18NA) .
Reconnect connector of the compres-
sor.
Refer to 10-5. "How to check inverter/
compressor".
Check the stop valve.
•
•
•
9
3-time fl ash
2.5 seconds OFF
Discharge tempera-
ture overheat 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 refrigerant circuit and the
refrigerant amount.
Refer to 10-5. "Check of LEV".
•
•
10
4-time fl ash
2.5 seconds OFF
Fin temperature /P.C.
board temperature
thermistor overheat
protection
Temperature of fi n temperature thermistor on the heat sink ex-
ceeds 167 ~ 176°F (75 ~ 80°C) or temperature of P.C. board tem-
perature 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".
•
•
•
11
5-time fl ash
2.5 seconds OFF
High pressure pro-
tection
Temperature of indoor coil thermistor exceeds 158°F (70°C) in
HEAT mode. Temperature of outdoor heat exchanger tempera-
ture thermistor exceeds 158°F (70°C) in COOL mode.
Check the refrigerant circuit and the
refrigerant amount.
Check the stop valve.
•
•
12
8-time fl ash
2.5 seconds OFF
Compressor syn-
chronous abnormal-
ity
The waveform of compressor current is distorted. Reconnect connector of the compressor.
Refer to 10-5. "How to check inverter/
compressor".
•
•
13
10-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.
•
•
14
12-time fl ash
2.5 seconds OFF
Each phase current
of compressor
Each phase current of compressor cannot be detected normally.
Refer to 10-5. "How to check inverter/
compressor".
•
15
13-time fl ash
2.5 seconds OFF
DC voltage DC voltage of inverter cannot be detected normally. Refer to 10-5. "How to check inverter/
compressor".
•
16
Outdoor
unit oper-
ates.
1-time fl ash
2.5 seconds OFF
Frequency drop by
current protection
Current from power outlet is nearing Max. fuse size. The unit is normal, but check the follow-
ing.
Check if the indoor fi lters are clogged.
Check if the refrigerant is short.
Check if the indoor/outdoor unit air cir-
culation is short cycled.
•
•
•
17
3-time fl ash
2.5 seconds OFF
Frequency drop by
high pressure pro-
tection
Temperature of indoor coil thermistor exceeds 131°F (55°C) in
HEAT mode, compressor frequency lowers.
Frequency drop by
defrosting in COOL
mode
Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
compressor frequency lowers.
18
4-time fl ash
2.5 seconds OFF
Frequency drop by
discharge tempera-
ture protection
Temperature of discharge temperature thermistor exceeds 232°F
(111°C), compressor frequency lowers.
Check the refrigerant circuit and the
refrigerant amount.
Refer to 10-5. "Check of LEV".
Refer to 10-5. "Check of outdoor
thermistors".
•
•
•
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. Flashing
(Example) When the fl ashing frequency is “2”.
1
Intelligent power module: MUZ-HE24NA
Power module: Other models
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
LED
Flashing →
LED
MUZ-HE24NA
MUZ-
HE09/12/15/18
NA
Inverter
P.C. board
(Parts side)
OBH686