Troubleshooting Check Table - Mitsubishi Electric SUZ-M25VA Technical & Service Manual

11-2. TROUBLESHOOTING CHECK TABLE

LED
No. Symptoms
indication
Outdoor unit 1-time blink
does not op-
1 every
erate.
2.5 seconds
2
3
6-time blink
4 2.5 seconds
OFF
11-time blink
5
2.5 seconds OFF
16-time blink
2.5 seconds
6
OFF
'Outdoor unit 2-time blink
stops and 2.5 seconds OFF
7
restarts 3
minutes later'
is repeated.
3-time blink
2.5 seconds OFF
8
4-time blink
2.5 seconds OFF
9
5-time blink
10 2.5 seconds OFF
8-time blink
11
2.5 seconds OFF
10-time blink
2.5 seconds OFF
12
12-time blink
13
2.5 seconds OFF
13-time blink
14
2.5 seconds OFF
Outdoor unit 1-time blink
15 operates. 2.5 seconds OFF
3-time blink
2.5 seconds OFF
16
4-time blink
2.5 seconds OFF
17
7-time blink
2.5 seconds OFF
18
8-time blink
2.5 seconds OFF
19
9-time blink
2.5 seconds OFF
20
Notes: 1. The location of LED is illustrated at the right figure. Refer to "11-6. Test point diagram and voltage".
2. LED is lighted during normal operation.
The blinking frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the blinking frequency is "2".
ON
2.5-second OFF
OFF
OCH684
Abnormal point/
check
Condition
code
Overcurrent protection cut-out operates 3 consecutive times
Outdoor power sys-
UP
within 1 minute after the compressor gets started.
tem
Outdoor thermistors Discharge temperature thermistor shorts, or opens during
U3
compressor running.
Fin temperature thermistor,
temperature thermistor, outdoor heat exchanger temperature
U4
thermistor or ambient temperature thermistor shorts, or opens
during compressor running.
Outdoor control system Nonvolatile memory data cannot be read properly.
FC
E8
Serial signal The communication fails between the indoor and outdoor unit
/
for 3 minutes.
E9
Stop valve/
Closed valve is detected by compressor current.
UE
Closed valve
A closed valve and air trapped in the refrigerant circuit are detected
PL Outdoor refrigerant
based on the temperature sensed by the indoor and outdoor thermistors
system abnormality
and the current of the compressor.
Overcurrent protec- Large current flows into intelligent power module.
tion
Discharge tempera- Temperature of discharge temperature thermistor exceeds
ture overheat pro- 116°C, compressor stops. Compressor can restart if discharge
tection 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 72 to 86°C or temperature of P.C. board temperature
perature thermistor thermistor on the inverter P.C.board exceeds 72 to 85°C.
overheat protection
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 start-up.
Each phase current Each phase current of compressor cannot be detected nor-
of compressor mally.
DC voltage DC voltage of inverter cannot be detected normally.
Frequency drop by When the input current exceeds approximately 7A(M25 )/
current protection 8A(M35)/12A(M50)14A(M60)/16A(M71), compressor
frequency lowers.
Frequency drop by Temperature of indoor coil thermistor exceeds 55°C in HEAT
high pressure pro-
mode, compressor frequency lowers.
tection
Frequency drop by Indoor coil thermistor reads 8°C or less in COOL mode, com-
defrosting in COOL pressor frequency lowers.
mode
Frequency drop by Temperature of discharge temperature thermistor exceeds
discharge tempera- 111°C, compressor frequency lowers.
ture protection
Low discharge tem- Temperature of discharge temperature thermistor has been
perature protection 50°C or less for 20 minutes.
(M25/35/50)
The overcurrent flows into PFC (Power factor correction :
PAM protection
IC820) or the bus-bar voltage reaches 394 V or more, PAM
PAM: Pulse Ampli-
stops and restarts.
tude Modulation
(M60/71)
Zero cross signal for PAM control cannot be detected.
Zero cross detecting
circuit
Inverter check mode The connector of compressor is disconnected, inverter check
mode starts.
0.5-second ON
2.5-second OFF
Condition
defrost thermistor, P.C. board
0.5-second ON
25 25
Remedy
• Reconnect connector of compressor.
• Refer to 11-5. "How to check in-
verter/compressor".
• Check stop valve.
• Refer to 11-5.F"Check of outdoor
thermistors".
• Replace inverter P.C. board.
• Check of indoor/outdoor connecting wire.
Replace indoor or outdoor P.C. board if
•
abnormality is displayed again.
• Check stop valve.
• Check for a gas leak in a connecting
piping, etc.
• Check stop valve.
•
Refer to 11-5. L "Check of outdoor
refrigerant circuit".
•
Reconnect connector of compressor.
• Refer to 11-5. "How to check in-
verter/compressor".
• Check stop valve.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 11-5. "Check of LEV".
I
• Check around outdoor unit.
• Check outdoor unit air passage.
• Refer to 11-5. "Check of outdoor
H
fan motor".
• Check refrigerant circuit and refrig-
erant amount.
• Check stop valve.
• Reconnect connector of compressor.
• Refer to 11-5. "How to check in-
verter/compressor".
• Refer to 11-5. "Check of outdoor
H
fan motor.
Refer to 11-5. "Check of inverter
•
J
P.C. board.
• Refer to 11-5. "How to check in-
verter/compressor".
• Refer to 11-5. "How to check in-
verter/compressor".
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.
• Check refrigerant circuit and refrig-
erant amount.
• Refer to 11-5. "Check of LEV".
I
• Refer to 11-5. "Check of outdoor
F
thermistors".
• Refer to 11-5. "Check of LEV".
I
• Check refrigerant circuit and refrig-
erant amount.
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.
•
Check if the connector of the com-
pressor is correctly connected.
• Refer to 11-5. "How to check
inverter/compressor".
Inverter P.C. board
Blinking →
LED