Mitsubishi Electric PUHZ-SW50VHA Service Manual page 34

Symptoms: Nothing is displayed on the remote controller. 2
Diagnosis flow
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 to 264 V AC?
YES
Check the status
of the indoor controller
board LED3 display.
Blinking.
Check the refrigerant address of
the outdoor unit. (SW1-3 to 1-6)
Is the refrigerant
address "0"?
YES
Check the LED display of the
outdoor unit after turning on the
main power again.
Is anything displayed?
Displayed.
Is "EA" or "Eb"
displayed?
YES
Check the voltage between S2
and S3 on the terminal block of
the outdoor unit.
17 to 28 V DC?
YES
OCH525C
NO
Not lighting.
Check the looseness or disconnection
of the indoor/outdoor connecting wire.
Are there looseness or
disconnection of the indoor/
outdoor connecting wire?
NO
NO
Not displayed.
NO
Is "E8" displayed?
NO
Can the unit be restarted?
Can all the indoor
unit be operated?
YES
NO
Cause
YES
• Breaking or poor contact
of the indoor/outdoor
connecting wire
• Normal
Only the unit which
has the refrigerant
address "0" supplies
power to the remote
controller.
• Defective outdoor
controller circuit
board
YES
• Defective outdoor
controller circuit
board
NO
• Defective indoor
controller board
• Influence of
electromagnetic noise
• Defective outdoor power
circuit board (SW40/50VHA)
or controller board (SW50VKA)
• Defective indoor
power board
34
LED display of the indoor
controller board
LED1 :
LED2 :
LED3 : or
Inspection method and
troubleshooting
• Fix the breaking or poor
contact of the indoor/outdoor
connecting wire.
• Set the refrigerant
address to "0". In case of
the multiple grouping
system, recheck the
refrigerant address again.
• Replace the outdoor
controller circuit board.
• Replace the outdoor
controller circuit board.
• Replace the indoor controller
board of the indoor unit which
does not operate.
• Not abnormal
There may be the influence
of electromagnetic noise.
Check the transmission wire
and get rid of the causes.
• Replace the outdoor power
circuit board (SW40/50VHA),
or controller board (SW50VKA)
• Replace the indoor
power board.