Nobu NBFS-48IDU Service Manual page 39

<Primary check>
(1) Is the room temperature higher than the preset temperature in cooling operation?
(2) Is the crossover cable connected properly?
Turn on power supply.
Does OPERATION
indication indicate?
YES
Does compressor delay
three minutes by
temperature changes or
others?
YES
Wait three minutes
Is it possible to detect AC
220-240V on terminal block
or contactor of compressor?
YES
Are all of compressor cords
normal?
YES
Is compressor motor winding
normal?(Check winding
resistor.)
YES
Is capacitor for compressor
normal?
YES
Is overload relay normal?
YES
Does compressor start?
YES
Does compressor stop after a
while?
YES
Is gas quantity normal?
(Check gas pressure.)
YES
Compressor is defective.
NO
Is resistance value of room
NO
sensor (Tr) and heat exchanger
sensor (TP1) normal?
NO
Microcontroller is defective or
miniature relay is defective..
NO
NO
Compressor is defective.
NO
Capacitor is defective.
NO
Overload relay is defective.
NO
Compressor is defective.
NO
Gas shortage (Gas leak)
YES
NO
YES
Check power supply.
Room sensor or heat
exchanger sensor is
defective.
Replace room sensor or
heat exchanger sensor.
Replace P.C. board.
Rewire or replace
defective cords.
Replace compressor.
Replace capacitor.
Replace overload relay.
Replace compressor.
Supply gas.
Replace compressor.