Troubleshooting Check Table - Mitsubishi Electric Mr.Slim MUZ-GC25NA - C1 Service Manual

9-3. TROUBLESHOOTING CHECK TABLE

MUZ-GC25/35NA
No. Symptom LED indication
Outdoor unit 1-time fl ash every
does not 2.5 seconds
1 operate.
2
3
6-time fl ash
4
2.5 seconds OFF
11-time fl ash
5
2.5 seconds OFF
14-time fl ash
6 2.5 seconds OFF
'Outdoor unit 2-time fl ash
stops and 2.5 seconds OFF
7 restarts 3
minutes later'
is repeated.
3-time fl ash
8 2.5 seconds OFF
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
12-time fl ash
12
2.5 seconds OFF
13-time fl ash
13
2.5 seconds OFF
14 Outdoor unit 1-time fl ash
operates. 2.5 seconds OFF
3-time fl ash
2.5 seconds OFF
15
4-time fl ash
2.5 seconds OFF
16
Outdoor unit 7-time fl ash
17 operates. 2.5 seconds OFF
8-time fl ash
2.5 seconds OFF
18
9-time fl ash
2.5 seconds OFF
19
NOTE: 1. The location of LED is illustrated at the right fi gure. Refer to 9-6.1.
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
2.5-second OFF
OFF
Abnormal point/
Condition
Outdoor power system Overcurrent protection stop is continuously performed 3 times
within 1 minute after the compressor gets started.
Outdoor thermistors Discharge temperature thermistor, fi n temperature thermistor,
defrost thermistor or P.C. board temperature thermistor shorts
or opens during compressor running.
Outdoor control system Nonvolatile memory data cannot be read properly. (When the
upper lamp of OPERATION INDICATOR lamp of the indoor unit
lights up or fl ashes 7-time.)
Serial signal The communication fails between the indoor and outdoor unit
for 3 minutes.
Stop valve / Closed Closed valve is detected by compressor current.
valve
Outdoor unit (Other Outdoor unit is defective.
abnormality)
Overcurrent protection Large current fl ows into intelligent power module.
Discharge temperature Temperature of discharge temperature thermistor exceeds 116
overheat protection °C, compressor stops. Compressor can restart if discharge
temperature thermistor reads 100°C or less 3 minutes later.
Fin temperature /P.C. Temperature of fi n temperature thermistor on the heat sink
board temperature exceeds 82 - 83°C or temperature of P.C. board temperature
thermistor overheat thermistor on the inverter P.C.board exceeds 81 - 85°C.
protection
High pressure Indoor coil thermistor exceeds 70°C in HEAT mode. Defrost
protection thermistor exceeds 70°C in COOL mode.
Compressor The waveform of compressor current is distorted.
synchronous
abnormality
Each phase current of Each phase current of compressor cannot be detected normally • Refer to 9-5.
compressor
DC voltage DC voltage of inverter cannot be detected normally.
Frequency drop by Current from power outlet reaches the protection current, and
current protection compressor frequency lowers.
Frequency drop by high Temperature of indoor coil thermistor exceeds 55°C in HEAT
pressure protection mode, compressor frequency lowers.
Frequency drop by Indoor coil thermistor reads 8°C or less in COOL mode,
defrosting in COOL compressor frequency lowers.
mode
Frequency drop by Temperature of discharge temperature thermistor exceeds 111°
discharge temperature C, compressor frequency lowers.
protection
Low discharge Temperature of discharge temperature thermistor has been 50°
temperature protection C or less for 20 minutes.
PAM protection PAM: The overcurrent fl ows into IGBT (Insulated Gate Bipolar
Pulse Amplitude transistor : TR821) or when the bus-bar voltage reaches 320 V
Modulation or more, PAM stops and restarts.
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
Condition
0.5-second ON
2.5-second OFF
30
Correspondence
• Reconnect connector of
compressor.
• Refer to 9-5. "How to check
inverter/compressor".
• Check stop valve.
• Refer to 9-5. "Check of outdoor
thermistors".
Replace inverter P.C. board.
Refer to 9-5. "How to check
miswiring and serial signal error.
• Check stop valve.
Refer to 9-2.2. "Flow chart of the
detailed outdoor unit failure mode
recall function".
• Reconnect connector of
compressor.
• Refer to 9-5. "How to check
inverter/compressor".
• Check stop valve.
• Check refrigerant circuit and
refrigerant amount.
• Refer to 9-5. "Check of LEV".
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 9-5. "Check of outdoor
fan motor".
• Check refrigerant circuit and
refrigerant amount.
• Check stop valve.
• Reconnect connector of
compressor.
• Refer to 9-5. "How to check
inverter/compressor".
"How to check
inverter/compressor".
• Refer to 9-5. "How to check
inverter/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
circulation is short cycled.
• Check refrigerant circuit and
refrigerant amount.
• Refer to 9-5. "Check of LEV".
• Refer to 9-5. "Check of outdoor
thermistors".
• Refer to 9-5. "Check of LEV".
• Check refrigerant circuit and
refrigerant amount.
This is not malfunction. PAM
protection will be activated in the
following cases;
Instantaneous power voltage
drop. (Short time power failure)
When the power supply voltage
is high.
Check if the connector of the
compressor is correctly connected.
Refer to 9-5. "How to check
inverter/compressor".
Inverter P.C. board (Parts side)
LED
Flashing
0.5-second ON