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Troubleshooting - Mitsubishi Electric MXZ-24UV -E2 Service Manual

Inverter-controlled multi system
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Table of Contents


12-1. Cautions on troubleshooting
1. Before troubleshooting, check the following:
1) Check the power supply voltage.
2) Check the indoor/outdoor connecting wire for mis-wiring.
2. Take care the following during servicing.
1) Before servicing the air conditioner, be sure to first turn off the remote controller to stop the unit, and then after con-
firming the horizontal vane is closed, turn off the breaker and / or disconnect the power plug.
2) Be sure to unplug the power cord before removing the front panel, the cabinet, the top panel, and the electronic con-
trol P.C. board.
3) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the
4) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
3. Troubleshooting procedure
1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.
To make sure, check how many times the abnormality indication is flashing on and off before starting service work.
2) If the electronic control P.C. board is supposed to be defective, check the copper foil pattern for disconnection and the
components for bursting and discoloration.
3) When troubleshooting, refer to the flow chart on this page and the check table on page 25 and 26.
12-2. Instruction of troubleshooting
• Check the indoor unit with referring to the indoor unit service manual, and confirm that there is any problem in the indoor unit.
Then, check the outdoor unit with referring to this page.
Operation start
Check the outdoor unit
LED indicator
A Check of power supply
See page 28.
• Indoor unit
• Cool or HEAT
serial signal
operation only
C Check of
B Check of
serial signal
See page 29.
See page 28.
Housing point
Lead wiring
• When cooling, heat
exchanger of
non-operating indoor
unit frosts.
•When heating, non
operating indoor unit
gets warm.
D Check of LEV
See page 30.
Display other than "00"
• When cooling,
• When heating,
dew drops in the
room does not get
E Check of
indoor unit
Check of mis-
inverter, compressor
See page 30.
Check mis-piping
Shortage of capacity
Refer to indicator list.
See page 25 and 26.
• When cooling,
room does not
E Check of
See page 30.


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