Mitsubishi Electric MUZ-AP25VG-E1 Service Manual page 59

12-3. TROUBLESHOOTING CHECK TABLE
No. Symptom LED indication
Outdoor unit 1-time blink every
does not 2.5 seconds
operate.
1
2
3
6-time blink
4
2.5 seconds OFF
11-time blink
5
2.5 seconds OFF
14-time blink
2.5 seconds OFF
6
16-time blink
2.5 seconds OFF
7
17-time blink
2.5 seconds OFF
8
'Outdoor unit 2-time blink
stops and 2.5 seconds OFF
9
restarts 3
minutes later'
is repeated.
3-time blink
2.5 seconds OFF
10
4-time blink
2.5 seconds OFF
11
5-time blink
2.5 seconds OFF
12
8-time blink
2.5 seconds OFF
13
10-time blink
2.5 seconds OFF
14
12-time blink
15
2.5 seconds OFF
13-time blink
2.5 seconds OFF
16
OBH789H
Abnormal point/
Condition
Outdoor power sys- Overcurrent protection cut-out operates 3 consecutive times
tem within 1 minute after the compressor gets started.
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.
P.C. board temperature thermistor shorts or opens during
compressor running.
Outdoor control sys- Nonvolatile memory data cannot be read properly.
tem (Upper lamp of OPERATION INDICATOR lamp on the indoor
unit lights up or blinks 7-time.)
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)
4-way valve/ The 4-way valve does not work properly.
Pipe temperature The indoor coil thermistor detects an abnormal temperature.
Outdoor refrigerant A closed valve and air trapped in the refrigerant circuit are
system abnormality detected based on the temperature sensed by the indoor and
outdoor thermistors and the current of the compressor.
Overcurrent protec- Large current flows into power module (IC700).
tion
Discharge tem- Temperature of discharge temperature thermistor exceeds
perature overheat 116°C, compressor stops. Compressor can restart if discharge
protection temperature thermistor reads 100°C or less 3 minutes later.
Fin temperature / Temperature of fin temperature thermistor on the heat sink
P.C. board tem- exceeds 75 ~ 86°C (MUZ-AP25/35/42/50/60)/75 ~ 80°C (MUZ-
perature thermistor
AP71) or temperature of P.C. board temperature thermis-
overheat protection
tor on the inverter P.C. board exceeds 72 ~ 85°C (MUZ-
AP25/35/42/50/60)/70 ~ 75°C (MUZ-AP71).
High pressure pro- Indoor coil thermistor exceeds 70°C in HEAT mode. Defrost
tection thermistor exceeds 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 startup.
Each phase current
Each phase current of compressor cannot be detected nor-
of compressor
mally.
Bus-bar voltage Bus-bar voltage of inverter cannot be detected normally.
(DC)
Condition
59
Remedy
• Reconnect connector of compres-
sor.
• Refer to 12-5. "How to check
inverter/compressor".
• Check stop valve.
• Refer to 12-5. "Check of outdoor
thermistors".
• Replace inverter P.C. board.
• Replace inverter P.C. board.
• Refer to 12-5. "How to check
miswiring and serial signal error.
• Check stop valve.
• Refer to 12-2.2. "Flow chart of the
detailed outdoor unit failure mode
recall function".
• Refer to 12-5. "Check of R.V.
coil".
• Replace the inverter P.C. board.
• Check for a gas leak in a
connecting piping etc.
• Check the stop valve.
• Refer to 12-5. "Check of outdoor
refrigerant circuit".
• Reconnect connector of compressor.
• Refer to 12-5. "How to check
inverter/compressor".
• Check stop valve.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 12-5.
"Check of LEV".
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 12-5. "Check of outdoor
fan motor".
• Check refrigerant circuit and refrig-
erant amount.
• Check stop valve.
• Reconnect connector of compressor.
• Refer to 12-5. "How to check
inverter/compressor".
• Refer to 12-5. "Check of outdoor
fan motor.
• Refer to 12-5. "Check of inverter
P.C. board.
• Refer to 12-5. "How to check
inverter/compressor".
• It occurs with following case.
Instantaneous power voltage drop.
(Short time power failure) (MUZ-
AP71)
• Refer to 12-5. "Check of power
supply". (MUZ-AP71)
• Refer to 12-5. "How to check in-
verter/compressor".