Mitsubishi Electric MUZ-JP WA Series Service Manual page 21

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 162 V DC
between CN211
and (–) ?
Replace the indoor power P.C.
board [and the indoor terminal 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.
Replace the indoor power P.C. board
[and the indoor terminal P.C. board].
OBH820
No
Does the voltage between CN211
(+) and
(+) rise to the range of 3 to 6 V DC within
Yes
12 seconds after EMERGENCY
OPERATION switch is pressed?
No
Does the voltage between CN10A
(+) and JPG (GND)(–) on the
indoor electronic control P.C. board
Yes fall to 2 V or less within 12 seconds
after EMERGENCY OPERATION
switch is pressed?
Replace the indoor fan motor.
Yes
(Unchanged)
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
ON again, then measure the voltage.
<Indoor power P.C. board>
1. Measure the voltage between CN211
2. Measure the voltage between CN211
<Indoor electronic control P.C. board>
3. Measure the voltage between CN10A (+) and JPG(GND)(–).
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.
(–) on the power P.C. board
No
Is it unchanged holding 0
or 15 V DC? No
(Changed)
Yes
(Unchanged)
Is it unchanged holding
0 or 5 V DC?
No
(Changed)
21
(+) and (–).
(+) and (–).
Replace the indoor fan motor.
Yes
Replace the indoor electronic
No
control P.C. board.
Measure the voltage CN10A (+) and JPG
(GND)(–) on the indoor electronic control P.C.
board when the fan motor is rotating.
Replace the indoor electronic control
P.C. board.