Mitsubishi Electric MSZ-A09NA Service Manual page 20

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.
Measure the resistance of resis-
tor (R111) on the indoor electronic
control P.C. board.
Indoor electronic
control P.C.Board
Varistor(NR11)
Fuse(F11)
CN211
Measure the resistance between
CN211 and of the indoor fan motor
connector.
Yes
Measure the resistance of the horizon-
tal vane motor coil.
(Refer to 8-5.)
Replace the indoor
electronic control P.C. board.
Yes
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?
Yes
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?
Yes
Replace indoor electronic control
P.C. board.
Is the resistance approx.
4 Ω?
Replace the indoor electronic control P.C. board.
20
Short/open circuit:
Replace the indoor fan motor.
Short/open circuit:
Replace the horizontal vane motor and the
indoor electronic control P.C. board.
No
No
1. The fan motor connector's
black.
2. Connect "+" of the tester to fan motor connector's
wire, and "-" to lead wire, otherwise the resistance can-
not be measured properly.
Replace indoor electronic control P.C. board
No and the indoor fan motor.
Replace the indoor electronic control P.C.
board and the indoor fan motor.
No
Yes
lead wire is red, whereas is
lead