Mitsubishi Electric MUZ-GE25VA, Service Manual

Page: 45 / 70

45
11-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication Abnormal point/
Condition
Condition Correspondence
1
Outdoor unit
does not op-
erate.
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 compres-
sor.
Refer to 11-5. "How to check in-
verter/compressor".
Check stop valve.
•
•
•
2
Outdoor thermistors Discharge temperature thermistor, fi n temperature thermistor,
defrost thermistor, P.C. board temperature thermistor, outdoor
heat exchanger temperature thermistor or ambient tempera-
ture thermistor shorts or opens during compressor running.
Refer to 11-5. "Check of outdoor
thermistors".
•
3
Outdoor control sys-
tem
Nonvolatile memory data cannot be read properly.
(The upper lamp of OPERATION INDICATOR lamp of the in-
door unit lights up or fl ashes 7-time.)
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 11-5. "How to check mis-
wiring 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 stop valve. •
6
14-time fl ash
2.5 seconds OFF
Outdoor unit
(Other abnormality)
Outdoor unit is defective. Refer to 11-2.2. "Flow chart of the
detailed outdoor unit failure mode
recall function".
•
7
'Outdoor unit
stops and
restarts 3
minutes later'
is repeated.
2-time fl ash
2.5 seconds OFF
Overcurrent protec-
tion
Large current fl ows into intelligent power module. Reconnect connector of compres-
sor.
Refer to 11-5. "How to check in-
verter/compressor".
Check stop valve.
•
•
•
8
3-time fl ash
2.5 seconds OFF
Discharge tempera-
ture overheat protec-
tion
Temperature of discharge temperature thermistor exceeds
116°C, compressor stops. Compressor can restart if discharge
temperature thermistor reads 100°C or less 3 minutes later.
Check refrigerant circuit and refrig-
erant amount.
Refer to 11-5. "Check of LEV".
•
•
9
4-time fl ash
2.5 seconds OFF
Fin temperature
/P.C. board tem-
perature thermistor
overheat protection
Temperature of fi n temperature thermistor on the heat sink
exceeds 75 ~ 80°C or temperature of P.C. board temperature
thermistor on the inverter P.C.board exceeds 70 ~ 75°C.
Check around outdoor unit.
Check outdoor unit air passage.
Refer to 11-5. "Check of outdoor
fan motor".
•
•
•
10
5-time fl ash
2.5 seconds OFF
High pressure pro-
tection
Indoor coil thermistor exceeds 70°C in HEAT mode. Defrost
thermistor exceeds 70°C in COOL mode.
Check refrigerant circuit and refrig-
erant amount.
Check stop valve.
•
•
11
8-time fl ash
2.5 seconds OFF
Compressor syn-
chronous abnormal-
ity
The waveform of compressor current is distorted. Reconnect connector of compres-
sor.
Refer to 11-5. "How to check in-
verter/compressor".
•
•
12
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 11-5. "Check of outdoor
fan motor.
Refer to 11-5. "Check of inverter
P.C. board.
•
•
13
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 11-5. "How to check in-
verter/compressor".
•
14
13-time fl ash
2.5 seconds OFF
DC voltage DC voltage of inverter cannot be detected normally. Refer to 11-5. "How to check in-
verter/compressor".
•
15 Outdoor unit
operates.
1-time fl ash
2.5 seconds OFF
Frequency drop by
current protection
Current from power outlet is nearing breaker capacity.
PFC module stops due to overcurrent.
(MUZ-GE60/71)
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.
•
•
•
16
3-time fl ash
2.5 seconds OFF
Frequency drop by
high pressure pro-
tection
Temperature of indoor coil thermistor exceeds 55°C in HEAT
mode, compressor frequency lowers.
Frequency drop by
defrosting in COOL
mode
Indoor coil thermistor reads 8°C or less in COOL mode, com-
pressor frequency lowers.
17
4-time fl ash
2.5 seconds OFF
Frequency drop by
discharge tempera-
ture protection
Temperature of discharge temperature thermistor exceeds
111°C, compressor frequency lowers.
Check refrigerant circuit and refrig-
erant amount.
Refer to 11-5. "Check of LEV".
Refer to 11-5. "Check of outdoor
thermistors".
•
•
•
18
Outdoor unit
operates.
7-time fl ash
2.5 seconds OFF
Low discharge tem-
perature protection
Temperature of discharge temperature thermistor has been
50°C or less for 20 minutes.
Refer to 11-5. "Check of LEV".
Check refrigerant circuit and refrig-
erant amount.
•
•
19
8-time fl ash
2.5 seconds OFF
MUZ-GE25/35/42/50
PAM protection
PAM: Pulse Ampli-
tude Modulation
The overcurrent fl ows into IGBT (Insulated Gate Bipolar tran-
sistor: TR821) or the bus-bar voltage reaches 320 V or more,
PAM stops and restarts.
This is not malfunction. PAM pro-
tection will be activated in the fol-
lowing cases:
1 Instantaneous power voltage
drop. (Short time power failure)
2 When the power supply voltage
is high.
MUZ-GE60/71
Zero cross detecting
circuit
Zero cross signal for PAM control cannot be detected.
20
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 11-5. "How to check
inverter/compressor".
•
NOTE:
1. The location of LED is illustrated at the right fi gure. Refer to 11-6.1.
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”.
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
LED
Flashing →
Inverter P.C. board
LED
→
MUZ-GE
25/35//42/50
MUZ-GE
60/71
Flashing