Troubleshooting Check Table; Heating - Mitsubishi Electric MXZ-2B20NA Service Manual

11-4. TROUBLESHOOTING CHECK TABLE

MXZ-2B/3B/4B
Indication
Symptom
No.
LED1(Red) LED2(Yellow)
Outdoor unit
1
Lighted Once
does not
operate.
2
Lighted Twice
3
Lighted 3 times
4
Lighted 4 times
5 Lighted 5 times
6
Lighted 7 times
7
Lighted 8 times
8
Lighted 11 times
9 Lighted 12 times
'Outdoor unit
stops and
Twice Not lighted
restarts 3
10
minutes
later' is
repeated.
3 times Not lighted
11
12 4 times Not lighted
13 5 times Not lighted
14 8 times Not lighted
15 9 times Not lighted
16 13 times Not lighted
17
Lighted 8 times
18 Lighted 11 times
Lighted 12 times
19
NOTE 1. The location of LED is illustrated at the right figure. Refer to 11-7.1.
2. LED is lighted during normal operation.
The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the flashing frequency is "2".
ON
2.5-second OFF
OFF
OBH560G
Abnormal point / Condition
LEV and drain pump The indoor unit detects an abnormality in the LEV and drain pump.
Overcurrent protection cut-out operates 3 consecutive times within 1 minute
after the compressor gets started, or converter protection cut-out or bus-bar
Outdoor power system
voltage protection cut-out operates 3 consecutive times within 3 minutes
after start-up.
A short circuit is detected in the thermistor during operation, or
Discharge temperature
an open circuit is detected in the thermistor after 10 minutes
thermistor
of compressor start-up.
Fin temperature
thermistor
A short or open circuit is detected in the thermistor during operation.
P.C board temperature
thermistor
Ambient temperature
A short or open circuit is detected in the thermistor during operation.
thermistor
A short circuit is detected in the thermistor during operation, or an
Outdoor heat exchanger
open circuit is detected in the thermistor after 5 minutes (in cooling)
temperature thermistor
and 10 minutes (in heating) of compressor start-up.
A short circuit is detected in the thermistor during operation, or
Defrost thermistor
an open circuit is detected in the thermistor after 5 minutes of
compressor start-up.
The nonvolatile memory data cannot be read properly.
Nonvolatile memory data
Current sensor Current sensor protection cut-out operates 2 consecutive times.
The communication protection cut-out between boards operates
Communication error
between P.C. boards 2 consecutive times.
Zero cross detecting
The protection cut-out of the zero cross detecting circuit operates
circuit
10 consecutive times.
IPM protection
Overcurrent is detected after 30 seconds of compressor start-up.
Overcurrent is detected within 30 seconds of compressor
Lock protection
start-up.
Discharge temperature The discharge temperature exceeds 240.8°F during operation.
protection Compressor can restart if discharge temperature thermistor reads 212°F
or less 3 minutes later.
Fin temperature
The fin temperature exceeds 188.6°F during operation.
protection
P.C. board temperature
The P.C. board temperature exceeds 158°F during operation.
protection
High-pressure is detected with the high-pressure switch (HPS)
during operation. (MXZ-3B24NA, MXZ-3B30NA, MXZ-4B36NA)
High-pressure
The outdoor heat exchanger temperature exceeds 158°F
protection
during cooling or the indoor gas pipe temperature exceeds 158°F
during heating.
A failure is detected in the operation of the converter during
Converter protection
operation.
The bus-bar voltage exceeds 400V or falls to 200V or below
Bus-bar voltage
protection (1) during compressor operating.
Bus-bar voltage The bus-bar voltage exceeds 400V or falls to 50V or below
during compressor operating.
protection (2)
A failure occurs 3 consecutive times within 30 seconds after the fan
Outdoor fan motor
gets started.
Current sensor A short or open circuit is detected in the current sensor during
protection
compressor operating.
Communication between P.C. Communication error occurs between the outdoor electronic control
boards protection P.C. board and power board for more than 10 seconds.
Zero cross signal cannot be detected while the compressor is
Zero cross detecting circuit
operating.
protection
0.5-second ON
2.5-second OFF
Condition
0.5-second ON
61
Remedy
• Refer to 11-6. "Check of LEV".
• Check the drain pump of the indoor unit.
• Check the connection of the compressor connecting
wire.
• Refer to 11-6. "How to check inverter/compressor".
• Check the stop valve.
• Refer to 11-6. "Check of outdoor thermistors".
• Refer to 11-6. "Check of outdoor thermistors".
• Replace the outdoor electronic control P.C. board.
• Refer to 11-6. "Check of outdoor thermistors".
• Replace the outdoor electronic control P.C. board.
• Replace the power board.
• Check the connecting wire between outdoor electronic control
P.C. board and power board.
• Check the connecting wire among outdoor electronic control
P.C. board, noise filter P.C. board and power board.
• Reconnect compressor connector.
• Refer to 11-6. "How to check inverter/compressor".
• Check the stop valve.
• Check the power module (PAM module).
• Check the amount of gas and refrigerant circuit.
• Refer to 11-6. "Check of LEV".
•Check refrigerant circuit and refrigerant amount.
•Refer to 11-6. "Check of outdoor fan motor".
• Check around of gas and the refrigerant circuit.
• Check of stop valve.
• Replace the power board.
• Check the voltage of power supply.
• Replace the power board or the outdoor electronic
control P.C. board.
• Refer to 11-6. "Check of bus-bar voltage".
• Refer to 11-6. "Check of outdoor fan motor".
• Replace the power board.
• Check the connecting wire between outdoor electronic control
P.C. board and power board.
• Check the connecting wire among outdoor electronic control
P.C. board, noise filter P.C. board and power board.
Outdoor electronic control P.C. board (Parts side)
MXZ-2B20NA
Lighted
MXZ-3B24NA, MXZ-3B30NA
MXZ-4B36NA
Lighted
LED2 LED1
LED1 LED2