Mitsubishi Electric MUZ-DW25VF, Service Manual

Page: 33 / 56

33
12-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication
Abnormal point/ Con-
dition
Condition Remedy
1
Outdoor unit
does not
operate. 1-time blink every
2.5 seconds Outdoor power sys-
tem Overcurrent protection cut-out operates 3 consecutive times
within 1 minute after the compressor gets started.
• Reconnect connector of compres-
sor.
• Refer to 12-5. "How to check
inverter/compressor".
• Check stop valve.
2
Outdoor thermistors
Discharge temperature thermistor, fin temperature thermis
-
tor, defrost thermistor, outdoor heat exchanger temperature
thermistor or ambient temperature thermistor shorts or opens
during compressor running.
• Refer to 12-5. "Check of outdoor
thermistors".
P.C. board temperature thermistor shorts or opens during
compressor running.
• Replace inverter P.C. board.
3
Outdoor control sys-
tem Nonvolatile memory data cannot be read properly.
(The upper OPERATION INDICATOR lamp on the indoor unit
lights up or blinks 7-time.)
• Replace inverter P.C. board.
4
6-time blink
2.5 seconds OFF Serial signal The communication fails between the indoor and outdoor unit
for 3 minutes.
• Refer to 12-5. "How to check
miswiring and serial signal error.
5
11-time blink
2.5 seconds OFF Stop valve/
Closed valve Closed valve is detected by compressor current.
• Check stop valve.
6
14-time blink
2.5 seconds OFF Outdoor unit
(Other abnormality) Outdoor unit is defective.
• Refer to 12-2.2. "Flow chart of the
detailed outdoor unit failure mode
recall function".
7
16-time blink
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 12-5. "Check of R.V.
coil".
• Replace the inverter P.C. board.
8
17-time blink
2.5 seconds OFF Outdoor refrigerant
system abnormality A closed valve and air trapped in the refrigerant circuit are
detected based on the temperature sensed by the indoor and
outdoor thermistors and the current of the compressor.
• Check for a gas leak in a
connecting piping etc.
• Check the stop valve.
• Refer to 12-5. “Check of outdoor
refrigerant circuit”.
9
'Outdoor unit
stops and
restarts 3
minutes later'
is repeated. 2-time blink
2.5 seconds OFF Overcurrent protec-
tion
Large current flows into
power module (IC700).
• Reconnect connector of compressor.
• Refer to 12-5. "How to check
inverter/compressor".
• Check stop valve.
10
3-time blink
2.5 seconds OFF Discharge tem-
perature overheat
protection 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 12-5. "Check of LEV".
11
4-time blink
2.5 seconds OFF Fin temperature /
P.C. board tem-
perature thermistor
overheat protection
Temperature of fin temperature thermistor on the heat sink
exceeds 75 ~ 86°C or temperature of P.C. board temperature
thermistor on the inverter P.C. board exceeds 72 ~ 85°C.
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 12-5. "Check of outdoor
fan motor".
12
5-time blink
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.
13
8-time blink
2.5 seconds OFF Compressor syn-
chronous abnormal-
ity The waveform of compressor current is distorted.
• Reconnect connector of compressor.
• Refer to 12-5. "How to check
inverter/compressor".
14
10-time blink
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 12-5. "Check of outdoor
fan motor.
• Refer to 12-5. "Check of inverter
P.C. board.
15
12-time blink
2.5 seconds OFF Each phase current
of compressor
Each phase current of compressor cannot be detected nor-
mally.
• Refer to 12-5. "How to check
inverter/compressor".
16
13-time blink
2.5 seconds OFF Bus-bar voltage
(DC) Bus-bar voltage of inverter cannot be detected normally.
• It occurs with following case.
Instantaneous power voltage drop.
(Short time power failure)
• Refer to 12-5. "Check of power
supply".
• Refer to 12-5. "How to check in-
verter/compressor".
17
Outdoor unit
operates. 1-time blink
2.5 seconds OFF Frequency drop by
current protection When the input current exceeds approximately 10A, compres-
sor frequency lowers. The unit is normal, but check the
following.
•
Check if indoor filters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air
circulation is short cycled.
18
3-time blink
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.
19
Frequency drop by
defrosting in COOL
mode Indoor coil thermistor reads 8°C or less in COOL mode, com-
pressor frequency lowers.
4-time blink
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 12-5. "Check of LEV".
• Refer to 12-5. "Check of outdoor
thermistors".
20
5-time blink
2.5 seconds OFF Outside temperature
thermistor protec-
tion When the outside temperature thermistor shorts or opens,
protective operation without that thermistor is performed.
• Refer to 12-5. Check of outdoor
thermistors.
OBH906A