Mitsubishi Electric MXZ-18TV Service Manual page 20

Troubleshooting check table <OUTDOOR UNIT>
LED 1 (red)
Lighting
Indication
Abnormal point
LED 1 LED 2
(red) (Yellow)
Lighting Twice Outdoor power system
Lighting 7 times Outdoor control system
6 times Goes out Indoor unit and LEV
DC voltage sensing cir-
Lighting 9 times
cuit
Indication
Abnormal point
LED 1 LED 2
(red) (Yellow)
Discharge temperature
Lighting 3 times
thermistor
Fin temperature ther-
Lighting 4 times
mistor
P.C. board temperature
Lighting 5 times
thermistor
Evaporation tempera-
Lighting 10 times
ture thermistor
Gas pipe temperature A
Lighting 11 times
thermistor
Gas pipe temperature B
Lighting 12 times
thermistor
Twice Goes out Over current protection
Discharge temperature
3 times Goes out
overheat protection
Fin temperature over-
4 times Goes out
heat protection
P.C. board temperature
4 times Goes out
overheat protection
LED 2 (yellow)
Lighting
Symptom: Outdoor unit does not operate.
Detecting method
When the compressor operation has been interrupted by overcurrent
protection continuously three times within 1 minute after start-up.
When the nonvolatile memory data cannot be read properly on the out-
door electronic control P.C. board.
When the drain abnormality is detected in the indoor unit and the indoor
unit coil temperature is too low, or when any abnormality is detected in
the components of indoor unit.
When DC voltage sensing circuit detects 57V or below or 395V or above
Symptom: Outdoor unit repeats to stop and restart in 3 minutes
Detecting method
When a short or open circuit occurs in the discharge temperature ther-
mistor during compressor running.
When a short or opern circuit occurs in the fin temperature thermistor
during compressor running.
When a short or open circuit occurs in the P.C. board temperature ther-
mistor during compressor running.
When a short or open circuit occurs in the evaporation temperature ther-
mistor during compressor running.
When a short or open circuit occurs in the gas pipe temperature A ther-
mistor during compressor running.
When a short or open circuit occurs in the gas pipe temperature B ther-
mistor during compressor running.
When over current 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 91: or above.
When the P.C. board temperature thermistor detects 79: or above.
Error mode
Normal
20
Check points
• Check the inverter / compressor.
Refer to "E" on page 24.
• Replace the outdoor electronic control
P.C. board.
• Check the abnormality indication on the
indoor unit.
• Check the LEV.
Refer to "D" on page 24.
• Replace the outdoor electronic control
P.C. board.
Check points
• Check the characteristic of the discharge
temperature thermistor.
Refer to "F" on page 25.
• Check the connector. (CN663)
• Check the characteristic of the fin temper-
ature thermistor.
Refer to "F" on page 25.
• Check the connector. (CN664)
• Replace the outdoor electronic control
P.C. board.
• Check the characteristic of the evaopra-
tion temperature thermistor.
Refer to "F" on page 25.
• Check the connector. (CN663)
• Check the characteristic of the gas pipe
temperature A thermistor.
Refer to "F" on page 25.
• Check the connector. (CN661)
• Check the characteristic of the gas pipe
temperature B thermistor.
Refer to "F" on page 25.
• Check the connector. (CN661)
• Check the inverter / compressor.
Refer to "E" on page 24.
• 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 refriger-
ant cycle.
• Check the outdoor unit air passage.
• Check the outdoor unit air passage.
• Check the outdoor fan motor.
Refer to "G" on page 25.
• Check the power module.
• Check the outdoor unit air passage.
• Check the outdoor fan motor.
Refer to "G" on page 25.
• Replace the outdoor electronic control
P.C. board.