Mitsubishi Electric MUZ-AP VG Series Service Manual page 36

10-6. 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.
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.
Is it unchanged holding 0
or 15 V DC?
Yes
(Unchanged)
Replace the indoor fan motor.
OBH788C
Pay enough 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
EMERGENCY OPERATION switch is pressed.
If more than 12 seconds passes, turn OFF the power supply and
No
turn it ON again, then measure the voltage.
<Indoor electronic control P.C. board>
1. Measure the voltage between CN211
2. Measure the voltage between CN211
Replace the indoor
electronic control P.C.
No
board.
(Changed)
(+) and
(+) and
If more than 12 seconds passes after EMERGENCY
OPERATION switch is pressed, the voltage measured at
2. above goes 0 V DC although the indoor P.C. board is
normal.
Is there 325 V DC
between CN211 (+)
and (–)?
Yes
Does the voltage between CN211
(+) and (–) on the indoor electronic
control P.C. board rise to the range of
3 to 6 V DC within 12 seconds after
EMERGENCY OPERATION switch is
pressed?
Yes
Replace the indoor fan motor.
36
(–).
(–).
Replace the indoor electronic
No control P.C. board.
Replace the indoor electronic
control P.C. board.
No