Troubleshooting; Cautions On Troubleshooting; Troubleshooting Procedure; How To Replace Batteries - Mitsubishi Electric MSC-A07WV Service Manual

NOTE
•
The operation settings are memorized when 10 seconds have passed after the remote controller was operated.
•
If main power is cut while AUTO START/STOP timer is active, the timer setting is cancelled.
•
If the unit has been off with the remote controller before power failure, the auto restart function does not work as the
power button of the remote controller is off.
•
To prevent breaker off due to the rush of starting current, systematize other home appliance not to turn on at the same
time.
•
When some air conditioners are connected to the same supply system, if they are operated before power failure, the
starting current of all the compressors may flow simultaneously at restart.
Therefore, the special counter-measures are required to prevent the main voltage-drop or the rush of the starting current
by adding system that allows the units to start one by one.
13

TROUBLESHOOTING

MSC-A07WV -
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MSC-A09WV -
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MSC-A12WV -
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13-1. 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 turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the electronic
control 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
components.
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 page 105, 106 and the check table on page 107 ~ 109.

4. How to replace batteries

Weak batteries may cause the remote controller malfunction.
In this case, replace the batteries to operate the remote controller normally.
1 Remove the front lid and insert batteries.
Then reattach the front lid.
NOTE : If the RESET button is not pressed, the remote controller may not operate correctly.
MU-A07WV - MUH-A07WV -
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MU-A09WV - MUH-A09WV -
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MU-A12WV - MUH-A12WV -
E1
Lead wiring
Insert the negative pole
of the batteries first.
Check if the polarity of
the batteries are correct.
MUX-A10WV -
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MUX-A19WV -
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MUX-A20WV -
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Housing point
2 Press the RESET button.
104
MUX-A25WV -
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MUX-A26WV -
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E1
RESET button
E1
E1