Mitsubishi Electric MUZ-D-NA Series Service Manual page 27

C Check of indoor electronic control P.C. board and indoor fan motor
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.
Indoor electronic
control P.C. board
Varistor (NR11)
Fuse(F11)
CN211
Measure the resistance between
CN211 and
connector.
Measure the resistance of the horizon-
tal vane motor coil.
Refer to 9-5.
Yes
Replace the indoor elec-
tronic control P.C. board.
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
(+) and (-) of the indoor fan motor
connector (to CN211 on the indoor
electronic control P.C. board) . 1, 2
Is the resistance 1 MΩ
or more?
Replace the indoor electronic
control P.C. board
Measure the resistance of cement
resistor (R111) on the indoor elec-
tronic control P.C. board.
Replace the indoor electronic control P.C. board.
Short circuit:
of the indoor fan motor
Replace the indoor fan motor.
Short circuit:
Replace the horizontal vane motor and the
indoor electronic control P.C. board.
Yes
No
No
Yes
1. The fan motor connector's
black.
2. Connect "+" of the tester to fan motor connector's
wire, and "-" to
not be measured properly.
Replace the indoor electronic control
No P.C. board and the indoor fan motor.
Yes
Is the resistance ap-
proximately 4 Ω? No
Yes
27
lead wire is red, whereas
lead
lead wire, otherwise the resistance can-
Replace the indoor electronic control P.C.
board and the indoor fan motor.
is