Symptoms: Nothing Is Displayed On The Remote Controller - Mitsubishi Electric PUZ-A18NHA4 Service Manual

Symptoms: Nothing is displayed on the remote controller

Diagnosis flow
Check the voltage between S1
and S2 on the terminal block
(TB4) of the indoor unit.
AC 187V to AC 253V?
YES
Check the voltage of indoor
controller board (CN2D).
DC 12V to DC 16V?
NO
Check the voltage of the unit after
removing the indoor power board
(CN2S).
DC 12V to DC 16V?
NO
NO
Check the voltage among L1 and L2
on the terminal block (TB1) of the
outdoor power circuit board.
AC 187V to AC 253V?
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.
AC 187V to AC 253V?
YES
YES
YES
Cause
NO
• Troubles concerning
power supply
NO
• Bad wiring of the
outdoor controller
board
• The fuses on the
outdoor
controller circuit
board are blown.
• Bad wiring of the
outdoor controller
board
• The fuses on the
outdoor
controller circuit
board are blown.
• Defective indoor
controller board
• Miswiring, breaking
or poor connection of
indoor/outdoor
connecting wire
• Defective indoor
power board
48
LED display of the indoor
controller board
LED1 :
LED2 :
LED3 :
Inspection method and
troubleshooting
• Check the power wiring
to the outdoor unit.
• Check the breaker.
• Check the wiring of the
outdoor unit.
• Check if the wiring is bad.
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.
• Check if miswiring, breaking
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
S1, S2 and S3 on the both
side of indoor/outdoor
terminal blocks.
• Replace the indoor
controller board.
• Check if there is miswiring
or breaking of wire.
• Replace the indoor
power board.