Mitsubishi Electric PUHZ-W85VAA Service Manual page 26

Symptoms: Nothing is displayed on the remote controller. 1
Diagnosis flow
Check the voltage between S1
and S2 on the terminal block
of the indoor unit which is used
to connect the indoor unit and
the outdoor unit.
198 to 264 V AC?
YES
OCH681
NO
Check the voltage among L(L ) and
3
N on the terminal block (TB1) of the
outdoor power circuit board.
198 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 to 264 V AC?
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.
• The fuses on the
indoor controller
circuit board are
blown.
• Defective indoor
controller board
26
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.
• Check if the fuses are
blown.
• Replace the indoor
controller board.