Mitsubishi Electric TRANE NTXFKS09A112AA Service Manual page 28

9-6. TROUBLESHOOTING FLOW
A Check of indoor fan motor
The indoor fan motor error has occurred, and the indoor fan does not operate.
Turn OFF the power supply.
Is there any foreign matter that interferes
the rotation of the line flow fan?
Yes
Remove the foreign matter and
adjust the line flow fan.
Is there 294/325 VDC
between CN211
and (–) ?
No
Replace the indoor electronic
control P.C. board.
The indoor fan motor error has occurred, and the indoor fan repeats "12-second ON and 30-second OFF" 3 times, and then stops.
Measure the voltage between CN211
(+) and (–) while the fan motor is
rotating.
OBHT752
Pay enough attention to the high voltage on the fan motor connector.
Turn ON the power supply, wait 5 seconds or more, and then press
EMERGENCY OPERATION switch.
Measure the supply voltage as follows within 12 seconds after EMER-
GENCY OPERATION switch is pressed.
If more than 12 seconds passes, turn OFF the power supply and turn it
No
ON again, then measure the voltage.
<Indoor electronic control P.C. board>
1. Measure the voltage between CN211
2. Measure the voltage between CN211
If more than 12 seconds passes after EMERGENCY OPERATION switch
is pressed, the voltage measured at 2. above goes 0 VDC although the
indoor P.C. board is normal.
Does the voltage between CN211
(+) and (–) on the indoor electronic
control P.C. board rise to the range
(+)
Yes of 2 to 6 VDC within 12 seconds after
EMERGENCY OPERATION switch is
pressed?
Is it unchanged holding 0
or 15 VDC?
Replace the indoor fan motor.
(+) and
(+) and
Yes
No
Indoor electronic
control P.C. Board
VARISTOR (NR11)
R111
CN211
No
(Changed)
Yes
(Unchanged)
28
(–).
(–).
Replace the indoor fan motor.
Fuse (F11)
CN151
Replace the indoor
electronic control P.C.
board.