Mitsubishi Electric MUZ-HA VF Series Service Manual page 33

10-6. TROUBLESHOOTING FLOW
A Check of indoor fan motor
HR25/35/42/50
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.
OBH822H
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 the
emergency operation switch.
Measure the supply voltage as follows within 12 seconds after the 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
Is there 325 V DC
between CN211
and
Does the voltage between CN211
(+) and
control P.C. board rise to the range of
3 to 6 V DC within 12 seconds after
the emergency operation switch is
pressed?
Replace the indoor fan motor.
Is it unchanged holding 0
or 15 V DC?
Yes
(Unchanged)
Replace the indoor fan motor.
33
(+) and (–).
(+) and (–).
(+)
No
(–) ?
Yes
(–) on the indoor electronic
No
Yes
Replace the indoor electronic
No control P.C. board.
(Changed)
If more than 12 seconds
*
passes after the emergency
operation switch is pressed,
the voltage measured at 2.
above goes 0 V DC although
the indoor P.C. board is
normal.
Replace the indoor electronic
control P.C. board.
Replace the indoor electronic
control P.C. board.