Nobu NBFS-48IDU Service Manual page 41

Trouble
Is the power applied to the
unit?
YES
Is the power normal? check
the voltage between L&N of
terminal block
YES
Press the power ON/OFF button of
wire control or remote control
YES
Does the beeper beep?
NO
Is the display all off?
Is the unit display normal?
NO
Check the failure code according to
the failure table
NO
Does the control ok?
YES
Check the connector on display
PCB connected to control PCB
Check the display PCB itself
YES
Does outdoor unit run?
Does the compressor run
NO
Does the indoor unit
NO
NO
NO
YES
NO
normally?
YES
run?
Check power supply mains or
interconnection wires
Check the wiring of indoor and
outdoor
YES
Does the control
PCB ok?
NO
Control PCB failure
Check the compressor ,wires
and it's capacitor.
Normal
Control failure