Hitachi RAS-10JH4 Service Manual page 88

5. Failure Phenomenon: Ventilation fan motor does not operate
<Situation> Ventilation fan motor does not operate.
Two way air exchange lamp blinks (lit for 4 seconds and off for 1 second).
"Timer lamp blinks 16 times" is not stored in the self-diagnosis memory.
<Assumed points of failure>
<Caution> If the two way air exchange switch is set to "fresh air in operation inhibited" or "fresh air in and exhaust operation
inhibited" position, operation of the ventilation fan motor is limited.
<Diagnosis flow>
Troubleshooting start
Is the connector (CN11) of the ventilation fan motor
inserted securely? Is there wiring disconnection?
Does voltage of approximately 12V exist between
pin of the connector (CN11) of the ventilation fan
②
motor?
Does voltage of approximately 5V (PWM signal) exist
between ② and pin?
③
Is there any factor to mechanically disturb rotation of the
ventilation fan?
Replace "Ventilation fan motor".
Mechanical lock of ventilation fan
Coming off of the connector or wiring disconnection of ventilation fan motor
Ventilation fan motor
Ventilation fan motor drive circuit
Yes
①
and
Yes
No
No
No
Yes
Remove the factor of mechanical lock.
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Repair the connector or wiring.
Replace "control board".