Mitsubishi Electric MSZ-AP25VG Service Manual page 28

C Check of indoor P.C. board and indoor fan motor
Turn OFF the power supply.
Remove the indoor fan motor connector
CN211 and the 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) [MSZ-AP25/35/42VG(K)]/reac-
tor (L112) [MSZ-AP50VG(K)] on the
indoor power P.C. board.
Terminal
P.C. board
Indoor electronic
control P.C. board
Fuse (F11)
Varistor LD201(T)
(NR11)
OBH788
Measure the resistance of indoor fan
motor.
Refer to 10-5.
Measure the resistance of the vane
motor coil.
Yes
Refer to 10-5.
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 (+) and
motor connector. 1, 2
Is the resistance 1MΩ or more?
Replace the fuse (F11). 3
Replace the indoor electronic control P.C. board.
LD201(M)
R111
L112
GND
Yes
No
No
Yes
1. The fan motor connector's
whereas
2. Connect "+" of the tester to fan motor connector's
lead wire, and "-" to
(-) of indoor fan
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
No indoor fan motor. 3
Yes
Is the resistance of resistor (R111)
[MSZ-AP25/35/42VG(K)] approxi-
mately 3.9Ω/reactor (L112) [MSZ-
AP50VG(K)] approximately 4.3Ω?
Yes
28
Short circuit:
Replace the indoor fan motor.
Short circuit:
Replace the vane motor and the indoor
electronic control P.C. board.
lead wire is red,
is black.
lead wire, otherwise the
Replace the indoor electronic
control P.C. board and the indoor
No
fan motor.