Hitachi RAK-18NH5 - Fan and System Stop Troubleshooting

No
Is 25-35V DC being generated
between blue and red of CN10,
CN15 in the "Hi" fan mode?
Is 5V DC being generated
between blue and yellow of CN10,
CN15?
Replace the indoor fan motor.
Check according to the proper
method for checking the power
circuit.
Is the microcomputer fan PWM
output (pin  ) ÒHiÓ in the fan
mode or are pulses being output
from it?
Replace Q901 or Q903.
Replace the microcomputer.
Perform final operation check.
Yes
Yes
Yes
No
No
2. Only indoor fan does not operate (others are normal)
3. Indoor fan speed does not change (others are normal)
Can the fan be stopped by remote
control?
No
The microcomputer fan PWM
output (pin )isÒHiÓ.
Replace the microcomputer.
Replace Q901 or Q903.
Replace the microcomputer.
Perform final operation check.
Yes
Yes
No
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