Mitsubishi Electric MFZ-KJ25VE Service Manual page 26

Check of indoor electronic control P.C. board and indoor fan motor
C
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 EMERGENCY OPERATION
switch?
No
Turn OFF the power supply.
Check both "parts side" and "pattern
side" of the indoor electronic control
P.C. board visually.
Measure the resistance of resis-
tor (R111) on the indoor electronic
control P.C. board.
Indoor electronic
control P.C. Board
VARISTOR (NR11)
R111
CN211
OBH666A
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
Yes
Is 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?
Yes
Measure the resistance between
CN211 (+) and (-) of indoor fan
motor connector. 1, 2
Is the resistance 1MΩ or more?
Yes
Replace the fuse (F11). 3
Replace the indoor electronic control P.C. board.
Fuse (F11)
CN151
Short circuit:
Replace the indoor fan motor.
Short circuit:
Replace the vane motor and the indoor
electronic control P.C. board.
No
No
1. The fan motor connector's
whereas
2. Connect "+" of the tester to fan motor connector's
lead wire, and "-" to
resistance cannot be measured properly.
3. Please replace the fuse after removing the indoor
electronic control P.C. board from the electrical box.
Replace the fuse (F11) and the
indoor fan motor. 3
No
Is the resistance of
resistor (R111) approxi-
No
mately 4 Ω?
Yes
26
lead wire is red,
is black.
lead wire, otherwise the
Replace the indoor
electronic control P.C.
board and the indoor fan
motor.