Mitsubishi MUZ-A18YV Service Manual page 32

1. Troubleshooting check table
LED 1 (Red)
Lighting
Indication
Abnormal point
LED 1 LED 2
(Red) (Yellow)
Lighting Twice Outdoor power system
Lighting 7 times Outdoor control system
Indication
Abnormal point
LED 1 LED 2
(Red) (Yellow)
3 times Discharge temperature
Lighting
thermistor
Fin temperature
thermistor
Lighting 4 times
P.C. board temperature
thermistor
Outdoor heat exchanger
Lighting 5 times
temperature thermistor
Lighting Current sensor
6 times
Communication error
Lighting 11 times
between P.C. boards
Lighting 12 times Zero cross signal error
Twice Goes out Overcurrent protection
3 times Goes out Discharge temperature
overheat protection
Fin temperature
4 times Goes out
overheat protection
Indication
Abnormal point
LED 1 LED 2
(Red) (Yellow)
4 times Goes out P.C. board temperature
overheat protection
5 times Goes out High-pressure protection
Power factor control
8 times Goes out
module protection
9 times Goes out DC voltage protection
Connectivity of indoor
11 times Goes out
and outdoor unit
13 times Goes out Fan motor protection
LED 2 (Yellow)
Lighting
Symptom: Outdoor unit does not operate.
Detecting method
When the compressor operation has been interrupted by over current
protection continuously three times within 1 minute after start-up, or
when power factor control module protection or DC control protection is
activated three times within 3 minutes after the compressor get started.
When the nonvolatile memory data cannot be read properly on the
outdoor electronic control P.C. board.
Symptom: It is repeated that outdoor unit stops and restarts 3 minutes later.
Detecting method
When a short or open circuit occurs in the discharge temperature
thermistor during compressor operating.
When a short or open circuit occurs in the fin temperature thermistor
during compressor operating.
When a short or open circuit occurs in the P.C. board temperature
thermistor during compressor operating.
When the outdoor heat exchanger temperature thermistor is short or
open while compressor is operating.
When the output from compressor current sensor becomes 25A or
more while the compressor is operating.
When the communication failure between the outdoor electronic control
P.C. board and power board occurs twice consecutively.
When the zero cross signal cannot be detected while the compressor is
operating.
When overcurrent is applied to the power module.
When the discharge temperature thermistor detects 116: or above.
(Protection will be released at 100: or below.)
When the fin temperature thermistor detects 87: or above.
Symptom: It is repeated that outdoor unit stops and restarts 3 minutes later
Detecting method
When the P.C. board temperature thermistor detects 70: or above.
When the outdoor heat exchanger temperature thermistor detects 69:
or more.
When high-pressure switch detects 4MPa or more. (MUZ-A26YV)
When the overcurrent to power factor controller occurs or the output
voltage from power factor controller becomes 400V or more.
When it's detected that DC voltage becomes 200V or less, or reaches
400V or more.
When the unusual signal is transmitted from the indoor unit.
When the fan motor current is 2A or more, or when the abnormality is
detected in the feedback signal from fan motor.
Error mode
Normal
32
Refer to page 35.
Check points
• Check the inverter/compressor.
• Replace the outdoor electronic control
P.C. board.
Check points
• Check the characteristic of the discharge
temperature thermistor.
• Check the connector. (CN661)
• Check the characteristic of the fin
temperature thermistor.
• Check the connector. (CN3)
• Replace the outdoor electronic control
P.C. board.
• Check the characteristic of the high
pressure protect thermistor.
• Check the connector. (CN661)
• Check if the connection lead wires of com-
pressor are correctly connected.
• Check if the connection wires between
outdoor electronic control P.C. board and
power board are correctly connected.
• Check if the connection wires between
noise filter P.C. board and power board are
correctly connected.
• Check the inverter/ compressor.
• Check the amount of gas.
• Check the indoor/ outdoor air flow for
short cycle.
• Check the indoor unit air filter for clogging.
• Check the amount of gas and the
refrigerant cycle.
• Check the outdoor unit air passage.
• Check the outdoor unit air passage.
• Check the outdoor fan motor.
• Check the power module.
Check points
• Check the outdoor unit air passage.
• Check the outdoor fan motor.
• Replace the outdoor electronic control
P.C. board.
• Check the outdoor unit air passage.
• Check the outdoor fan motor.
• Check the input voltage.
• Check the inverter.
• Check the voltage of power supply.
• Check the inverter.
• Check if the indoor unit can be connected
with the outdoor unit.
• Check the outdoor fan motor.
• Check the fan motor connector.