Mitsubishi Electric City Multi CMH-WM250V-A, Service Handbook

Page: 261 / 436

[8-2 ME remote Controller Problems ]
6
- chapter 8 BS_08_E
8 Troub
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8-2-2 The LCD Momentarily Lights Up and Then Goes Off.
1. Phenomena
When the remote controller operation SW is turned on, a temporary operation display is indicated, and the display lights out
immediately.
2. Cause
1) The power is not supplied to the indoor unit.

The main power of the indoor unit (AC220V) is not on.

The connector on the indoor unit board has come off.

The fuse on the indoor unit board has melted.

Transformer failure and disconnected wire of the indoor unit

The indoor unit board failure
2) The outdoor control board failure
As the indoor unit does not interact with the outdoor unit, the outdoor unit model cannot be recognized.
3. Check method and remedy
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
*1
*1
Check LED1 on the
indoor unit control board.
Is it lit?
When it is lit
When it is off
or cannot be checked
Check for the change of LED
display by operating dip
switch for self-diagnosis.
Check voltage of the power supply
terminal on the indoor unit.
AC220V?
Check the fuse on
the circuit board.
Melted?
Check 200V circuit for
short circuit and ground fault
Check the connection
of the connector.
Check the main power of
the power supply wire
Turn on the
power again.
Connector contact failure
Disconnected?
Check the resistance value
of the transformer
Within specification?
Check the cause of the
disconnected transformer.
Ground fault on the circuit board
Ground fault of the sensor and the LEV
Check self-diagnosis function
of outdoor unit
Changed?
Changed?
Outdoor unit board failure
Check self-diagnosis function of
outdoor unit after the power on.
Accidental
error
Indoor unit control
board failure
Correct
the error.
*1. Refer to the parts catalog “transformer check”.
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