Mitsubishi Electric Mr.Slim PUZ-HA42NKA Service Manual page 41

Symptoms: Nothing is displayed on the remote controller 1
Diagnosis flow
Check the voltage between S1
and S2 on the terminal block
(TB4) of the indoor unit.
187 to 253 V AC?
YES
Check the voltage of indoor
controller board (CN2D).
12 to 16 V DC?
NO
Check the voltage of the unit after
removing the indoor power board
(CN2S).
12 to 16 V DC?
NO
OCH567
NO
Check the voltage among L1 and L2
on the terminal block (TB1) of the
outdoor power circuit board.
187 to 253 V AC?
YES
Check the voltage between S1
and S2 on the terminal block
(TB1) of the outdoor unit which
is used to connect the indoor
unit and the outdoor unit.
187 to 253 V AC?
YES
YES
YES
Cause
NO
Troubles concerning
power supply
NO
outdoor controller
board
outdoor
controller circuit
board are blown.
outdoor controller
board
outdoor
controller circuit
board are blown.
controller board
or poor connection of
indoor/outdoor
connecting wire
power board
LED display of the indoor
controller board
LED1 :
LED2 :
LED3 :
Inspection method and
troubleshooting
to the outdoor unit.
outdoor unit.
Check if the fuses are blown.
The fuses on the outdoor
controller circuit board will
be blown when the indoor
/outdoor connecting wire
short-circuits.
or poor contact is causing this
problem. Indoor/outdoor
connecting wire is polarized
3-core type. Connect the
indoor unit and the outdoor
unit by wiring each pair of
side of indoor/outdoor
terminal blocks.
controller board.
Check if there is miswiring
or breaking of wire.
power board.