Carrier 619FB Service Manual page 23

2. Malfunction of Blocked Protection of IDU Fan Motor H6
Start
Turn the fan blades
by hand under
power-off condition
Do the fan blades rotate
smoothly with little to no
resistance
Yes
Under power-off condition,
check whether the wiring terminal
between indoor fan and main
board is loose.
No
Connect power and restart the unit.
Test whether the voltage between terminal 1 and terminal 2
of motor interface is within 280~310VDC.
Yes
Then check whether the voltage
between terminal 2 and terminal 3
of the motor interface is 15VDC.
Yes
Then check whether there is voltage
between terminal 2 and terminal 4
of the motor interface.
Yes
It's the malfunction of motor.
Replace a new motor that is
of the same model.
Fig. 26 – Troubleshooting
Adjust the motor and blade
assembly so the rotor can run
No
smoothly.
Turn unit on
to check whether the
No
malfunction is
eliminated.
Reinsert the wiring
Yes
terminal of indoor fan.
Turn unit on
to check whether the
No
malfunction is
eliminated.
It's the malfunction of main board.
No
Replace a new main board that is
of the same model.
It's the malfunction of main board.
No
Replace a new main board that is
of the same model.
It's the malfunction of main board.
No
Replace a new board of the same
model.
End
23
Yes
Yes