Troubleshooting Check Table - Mitsubishi Electric Mr.Slim MUZ-FE09NA Service Manual

10-3. TROUBLESHOOTING CHECK TABLE

No. Symptom LED indication
Outdoor unit 1-time fl ash every
does not oper- 2.5 seconds
1 ate.
2
3
6-time fl ash
4
2.5 seconds OFF
11-time fl ash
5
2.5 seconds OFF
14-time fl ash
2.5 seconds OFF
6
'Outdoor unit 2-time fl ash
stops and 2.5 seconds OFF
7 restarts 3 min-
utes later' is
repeated.
3-time fl ash
2.5 seconds OFF
8
4-time fl ash
2.5 seconds OFF
9
5-time fl ash
10 2.5 seconds OFF
8-time fl ash
2.5 seconds OFF
11
10-time fl ash
2.5 seconds OFF
12
12-time fl ash
13
2.5 seconds OFF
13-time fl ash
14
2.5 seconds OFF
15 Outdoor unit 1-time fl ash
operates. 2.5 seconds OFF
3-time fl ash
2.5 seconds OFF
16
4-time fl ash
2.5 seconds OFF
17
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".
ON
2.5-second OFF
OFF
Abnormal point/ Con-
dition
Outdoor power sys- Overcurrent protection stop is continuously performed 3 times
tem within 1 minute after the compressor gets started, or failure of
restart of compressor has repeated 24 times.
Outdoor thermistors Discharge temperature thermistor, fi n temperature thermistor,
defrost thermistor, outdoor heat exchanger temperature ther-
mistor, P.C. board temperature thermistor or ambient tempera-
ture thermistor shorts or opens during compressor running.
Outdoor control sys- Nonvolatile memory data cannot be read properly.
tem
[POWER lamp (MSZ-FE09/12NA)/the upper lamp of OPERA-
TION INDICATOR lamp (MSZ-FE18NA) of the indoor unit
lights up or fl ashes 7 times.]
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
Outdoor unit Outdoor unit is defective.
(Other abnormality)
Overcurrent protec- Large current fl ows into intelligent power module.
tion
MUZ-FE09/12NA
When overcurrent protection occurs within 10 seconds after
compressor starts, compressor restarts after 15 seconds.
Discharge tempera- Temperature of discharge temperature thermistor exceeds 241
ture overheat protec- °F (116°C), compressor stops. Compressor can restart if dis-
tion charge temperature thermistor reads 212°F (100°C) or less 3
minutes later.
Fin temperature Temperature of fi n temperature thermistor on the heat sink
/P.C. board tem- exceeds 167 ~ 176°F (75 ~ 80°C) or temperature of P.C. board
perature thermistor temperature thermistor on the inverter P.C. board exceeds 158
overheat protection ~ 167°F (70 ~ 75°C).
High pressure pro- Temperature of indoor coil thermistor exceeds 158°F (70°C) in
tection HEAT mode. Temperature of outdoor heat exchanger tempera-
ture 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 start-up.
Each phase current Each phase current of compressor cannot be detected nor-
of compressor mally.
DC voltage DC voltage of inverter cannot be detected normally.
Frequency drop by Current from power outlet is nearing Max. fuse size.
current protection
Frequency drop by Temperature of indoor coil thermistor exceeds 131°F (55°C) in
high pressure pro- HEAT mode, compressor frequency lowers.
tection
Frequency drop by Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
defrosting in COOL compressor frequency lowers.
mode
Frequency drop by Temperature of discharge temperature thermistor exceeds 232
discharge tempera- °F (111°C), compressor frequency lowers.
ture protection
0.5-second ON
2.5-second OFF
Condition
0.5-second ON
21
Remedy
• Reconnect connector of compres-
sor.
• Refer to 10-5. "How to check in-
verter/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 10-2.2. "Flow chart of the
detailed outdoor unit failure mode
recall function".
• Reconnect connector of compres-
sor.
• Refer to 10-5. "How to check in-
verter/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 compres-
sor.
• Refer to 10-5. "How to check in-
verter/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 in-
verter/compressor".
• Refer to 10-5. "How to check in-
verter/compressor".
The unit is normal, but check the
following.
• Check if indoor fi lters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air cir-
culation is short cycled.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
• Refer to 10-5. "Check of outdoor
thermistors".
Inverter P.C. board (Parts side)
MUZ-FE09
LED
/12NA
Flashing →
MUZ-FE
18NA
LED