Mitsubishi Electric Mr.Slim MUZ-A17NA, Service Manual

Page: 43 / 84

43
MUZ-A09/12/15/17NA MUY-A15/17NA
No. Symptom LED indication Abnormal point / Condition Condition Correspondence
1
Outdoor unit
does not oper-
ate.
1-time fl ash every
2.5 seconds
Outdoor power sys-
tem
Overcurrent protection stop is continuously performed 3 times
within 1 minute after the compressor gets started.
• Reconnect connector of compressor.
• Refer to 10-5. "How to check in-
verter/compressor".
• Check stop valve.
2
Outdoor thermistors Discharge temperature thermistor, fi n temperature thermistor,
defrost thermistor (MUZ), P.C. board temperature thermistor or
ambient temperature thermistor shorts or opens during com-
pressor running.
• Refer to 10-5. "Check of outdoor
thermistors".
3
Outdoor control sys-
tem
Nonvolatile memory data cannot be read properly. 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
miswiring and serial signal error".
5
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
detailed outdoor unit failure mode
recall function".
6
'Outdoor unit
stops and
restarts 3 min-
utes later' is
repeated.
2-time fl ash
2.5 seconds OFF
Overcurrent protec-
tion
24 A (09/12) / 26.5 A (15/17) current fl ows into intelligent power
module.
• Reconnect connector of compressor.
• Refer to 10-5. "How to check in-
verter/compressor"
• Check stop valve.
7
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 dis-
charge temperature thermistor reads 212°F (100°C) or less 3
minutes later.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
8
4-time fl ash
2.5 seconds OFF
Fin temperature /
P.C. board tempera-
ture thermistor over-
heat protection
Temperature of fi n temperature thermistor on the heat sink
exceeds 180°F (82°C) (09/12) / 188°F (86.5°C) (15/17) or tem-
perature of P.C. board temperature thermistor on the inverter
P.C. board exceeds 176°F (80°C).
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 10-5. "Check of outdoor
fan motor".
9
5-time fl ash
2.5 seconds OFF
High pressure pro-
tection
Indoor coil thermistor exceeds 158°F (70°C) in HEAT mode.
(MUZ)
Defrost thermistor exceeds 158°F (70°C) in COOL mode.
• Check refrigerant circuit and refrig-
erant amount.
• Check stop valve.
10
8-time fl ash
2.5 seconds OFF
Compressor syn-
chronous abnormal-
ity
The waveform of compressor current is distorted. • Reconnect connector of compressor.
• Refer to 10-5. "How to check in-
verter/compressor"
11
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".
12
12-time fl ash
2.5 seconds OFF
Each phase current
of compressor
Each phase current of compressor cannot be detected nor-
mally.
• Refer to 10-5. "How to check
inverter/compressor"
13
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 in-
verter/compressor".
14 Outdoor unit
operates.
1-time fl ash
2.5 seconds OFF
Frequency drop by
current protection
Current from power outlet exceeds 9.2 A (09/12) / 11.1 A
(15/17) compressor frequency lowers.
The unit is normal, but check the fol-
lowing.
• Check if indoor fi lters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air cir-
culation is short cycled.
15
3-time fl ash
2.5 seconds OFF
Frequency drop by high
pressure protection
Temperature of indoor coil thermistor exceeds 131°F (55°C) in
HEAT mode (MUZ), compressor frequency lowers.
Frequency drop by de-
frosting in COOL mode
Indoor coil thermistor reads 46°F (8°C) or less in COOL mode,
compressor frequency lowers.
16
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 refrigerant circuit and refrig-
erant amount.
• Refer to 10-5. "Check of LEV".
• Refer to 10-5. "Check of outdoor
thermistors".
17
Outdoor unit
operates.
7-time fl ash
2.5 seconds OFF
Low discharge tem-
perature protection
Temperature of discharge temperature thermistor has been
122°F (50°C) or less for 20 minutes.
• Refer to 10-5. "Check of LEV".
• Check refrigerant circuit and refrig-
erant amount.
18
8-time fl ash
2.5 seconds OFF
PAM protection
PAM:
Pulse
Amplitude
Modulation
The overcurrent fl ows into IGBT (Insulated Gate Bipolar tran-
sistor: TR821) or when the bus-bar voltage reaches 320 V or
more, PAM stops and restarts.
This is not malfunction.
PAM protection will be activated in
the following cases:
lnstantaneous power voltage drop
(Short time power failure)
When the power supply voltage is high.
19
9-time fl ash
2.5 seconds OFF
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
Check if the connector of the com-
pressor is correctly connected.
Refer to 10-5. "How to check in-
verter/compressor".
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".
Inverter P.C. board (Parts side)
LED
Flashing
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON 0.5-second ON
10-3. TROUBLESHOOTING CHECK TABLE