MITSUBISHI ELECTRIC MXZ-24UV - Manual (Page 31)

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F F Check of thermistor
Normal
Yes
No
Abnormal
Reconnect the connector (CN661, CN662 and CN663) and disconnect the lead wire leading to the compressor.
Turn on power supply to the indoor and outdoor unit. Three minutes later EMERGENCY OPERATION starts.
Thermistor
Defrost thermistor
Discharge temperature thermistor
Evaporation temperature thermistor
Gas pipe temperature thermistor (Unit A)
Gas pipe temperature thermistor (Unit B)
Gas pipe temperature thermistor (Unit C)
Fin temperature thermistor LED
E7
E6
E9
F5
F6
F7
d4
Symbol
RT62
RT61
RT63
RT66
RT67
RT68
RT65
Connector, Pin No.
Between CN661 pin1 and pin2
Between CN661 pin3 and pin4
Between CN661 pin5 and pin6
Between CN662 pin1 and pin2
Between CN662 pin3 and pin4
Between CN662 pin5 and pin6
Between CN663 pin1 and pin2
Start
Disconnect the connector in the electronic control P. C. board (see above table), and
measure the resistance of thermistor to check whether the thermistor is normal or not.
Does thermistor operate 10 minutes or more though the
thermistor abnormality is not displayed?
Replace the thermistor
Normal
Replace the electronic
control P. C. board.
G G Check of fan motor
Abnormal
Normal
Yes
No
No
Yes
No
Yes
Start
Check the connection of connector (CN851, CN852) in the fan motor relay connector and electronic control P. C. board
at the noise filter P. C. board and connector (CN901, CN902) in the noise filter board.
Disconnect the fan motor connector, and measure the resistance of the
fan motor winding to check the winding characteristic.
Is there voltage of 230V AC?
1. Turn off power supply of the indoor and outdoor unit, and disconnect the connector
(CN851, CN852).
2. Is the voltage 0V, when the voltage between CN852 pin1 (+) and CN851 pin1 (-),
pin2 (-), or pin3 (-) are measured after the power supply is turned on the outdoor unit?
Replace the fan motor
Replace the electronic
control P. C. board
Is there voltage of 12V DC between CN852 pin1 (+) and pin3 (-), when power supply
turns on the indoor unit and EMERGENCY OPERATION starts in three minutes.
1. Disconnect the lead wire leading to the compressor. Turn on power supply to the
indoor and outdoor unit. Three minutes later, EMERGENCY OPERATION starts.
2. Check the voltage between pin 2 and pin 3, pin 2 and pin 5, pin 2 and pin 6 at the fan motor connector.
Replace the noise filter P. C. board
• When thermistor is abnormal. (When the LED display is a table below.)
• Fan motor does not operate. Or, fan motor stops at once’ after fan motor operates.
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