Troubleshooting Flow - Mitsubishi Electric MSZ-FD09NA Service Manual

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 fl ow fan?
Yes
Remove the foreign matter and
adjust the line fl ow fan.
Is there 294/325 VDC between
CN211 (+) and
voltage between CN211 (+) and (-)
rise to the range of 3 to 6 VDC within
12 seconds after EMERGENCY
OPERATION switch is pressed?
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.
Pay careful attention to the high voltage on the fan motor connector CN211.
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.
No If more than 12 seconds passes by, turn OFF the power supply and
turn ON it again, then measure the voltage.
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 electronic control P.C. board is normal
(-), and does the
Yes
No
Is it unchanged holding
0 or 15 VDC?
Replace the indoor fan motor.
Replace the indoor fan motor.
Replace the indoor electronic control P.C. board.
No
(Changed)
Yes
(Unchanged)
29
(+) and (-).
(+) and (-).
CN211
Indoor electronic
control P.C. board