Mitsubishi Electric PUHZ-SP125VKA Service Manual page 47

Symptoms: Nothing is displayed on the remote controller 1
Check the voltage between S1
and S2 on the terminal block
(TB4) of the indoor unit which
is used to connect the indoor
unit and the outdoor unit.
198 V AC to 264 V AC?
YES
Check the voltage of indoor
controller board (CN2D).
12 V DC to 16 V DC ?
NO
Check the voltage of the unit after
removing the indoor power board
(CN2S).
12 V DC to 16 V DC ?
NO
OCH671
Diagnosis flow
NO
Check the voltage among L(L
N on the terminal block (TB1) of the
outdoor power circuit board.
198 V AC to 264 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.
198 V AC to 264 V AC?
YES
YES
YES
Cause
) and
3
NO
• Troubles concerning
power supply.
NO
• Bad wiring of the
outdoor controller
board.
• The fuses on the
outdoor controller
circuit board are
melting.
• Bad wiring of the
outdoor controller
board.
• The fuses on the
outdoor controller
circuit board are
melting.
• Defective indoor
controller board
• Miswiring, breaking
or poor connection
of indoor/outdoor
connecting wire
• Defective indoor
power board
47
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
melting.The fuses on the
outdoor controller circuit
board will be melting 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.