Mitsubishi Electric MUZ-HA VF Series Service Manual page 35

C Check of indoor P.C. board and indoor fan motor
HR25/35/42/50
Turn OFF the power supply.
Remove indoor fan motor connector CN211
and vane motor connector CN151 from the
indoor electronic control P.C. board and turn
ON the power supply.
Does the unit operate with the remote
controller?
Does OPERATION INDICATOR lamp light
up by pressing the emergency operation
switch?
No
Turn OFF the power supply.
Check both "parts side" and "pattern
side" of the indoor power P.C. board
visually.
1. Please replace the fuse after removing the
*
indoor power P.C. board from the electrical
box.
2. The fan motor connector's lead wire is red,
*
whereas is black.
3. Connect "+" of the multimeter to fan motor
*
connector's lead wire, and "-" to
wire, otherwise the resistance cannot be
measured properly.
Measure the resistance of resistor (R111)
on the indoor power P.C. board.
Indoor electronic
control P.C. board
R111
12 VDC
GND
FUSE (F11)
Varistor (NR11)
OBH822H
Measure the resistance between
CN211
motor connector.
Measure the resistance of the vane
motor coil.
Yes
Refer to 10-5.
Replace the varistor (NR11)
and fuse (F11).
Are the varistor (NR11)
burnt and the fuse (F11)
blown?
Be sure to check both the fuse
and the varistor in any case.
Is the fuse (F11) blown
only?
Measure the resistance between
CN211 (+) and
motor connector.
lead
Is the resistance 1MΩ or more?
Replace the fuse (F11).
5 VDC
and of the indoor fan
1
*
Yes
No
No
Yes
(-) of indoor fan
2, 3
* *
Replace the fuse (F11) and the
indoor fan motor. *3
No
Yes
1
*
Is the resistance of resistor (R111)
approximately 4 Ω ?
Yes
Replace the indoor electronic control P.C. board.
35
Short circuit:
Replace the indoor fan motor.
Short circuit:
Replace the vane motor and the indoor
electronic control P.C. board.
Replace the indoor electronic
control P.C. board and the indoor
No
fan motor.