Mitsubishi MXZ-*C*NA Series Service Manual page 27

C Check of indoor P.C. board and indoor fan motor
Turn OFF the power supply.
Remove indoor fan motor connector CN211
from indoor power P.C. board 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 EMERGENCY OPERATION
switch?
No
Turn OFF the power supply.
Check both "parts side" and "pattern
side" of the indoor power P.C. board
visually.
Measure the resistance of
resistor (R111) on the indoor
power P.C. board.
Indoor power
P.C. board
CN211
Indoor electronic
control P.C. board
CN10A
GND(JPG)
OBH736A
Yes
Replace the varistor (NR11)
and fuse (F11). 3
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
motor connector. 1, 2
Is the resistance 1MΩ or more?
Replace the fuse (F11). 3
Fuse (F11)
Varistor
(NR11)
R111
Measure the resistance of indoor fan
motor.
Refer to 9-5.
Measure the resistance of the vane
motor coil.
Refer to 9-5.
Yes
No
No
Yes
(+) and (-) of indoor fan
No
Yes
Is the resistance of
resistor (R111) approximately
3.9 Ω ?
Yes
Is there approximately 5 V DC between
5 V (+) and JPG (GND) (-) of the
indoor electronic control P.C. board?
Is there approximately 12 V DC
between 12 V (+) and JPG (GND) (-)
of the indoor electronic control P.C.
board?
No
Is connector CN102 on the
indoor electronic control P.C.
board or lead wires discon-
nected?
No
Replace the indoor electronic control P.C. board.
27
Short circuit:
Replace the indoor fan motor.
Short circuit:
Replace the vane motor and the indoor
electronic control P.C. board.
1. The fan motor connector's lead wire is red,
whereas is black.
2. Connect "+" of the tester to fan motor connector's
lead wire, and "-" to lead wire, otherwise the
resistance cannot be measured properly.
3. Please replace the fuse after removing the indoor
power P.C. board from the electrical box.
Replace the fuse (F11) and the
indoor fan motor. 3
Replace the indoor
power P.C. board and
No
the indoor fan motor.
Replace the indoor fan motor.
Yes
Connect the connector or repair discon-
Yes nection.