Mitsubishi Electric MSZ-A09NA Service Manual page 20

The unit does not operate with the remote controller.
Also, OPERATION INDICATOR lamp does not light up by pressing EMERGENCY OPERATION switch.
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.
Indoor electronic
control P.C.Board
Varistor(NR11)
Fuse(F11)
CN211
Measure the resistance between CN211 3
and 4 of the indoor fan motor connector.
Yes
Measure the resistance of the horizontal vane
motor coil.
Refer to 8-5.
Replace the indoor electronic
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
1(+) and 3(-) of the indoor fan
motor connector (to CN211 on the
indoor electronic control P.C. board) .
w1,w2
Is the resistance 1M"
or more?
Replace the indoor electronic
control P.C. board
Measure the resistance of cement
resistance R111 on the indoor electronic
control P.C. board.
Yes
No
No
Yes
w1. The fan motor connector's 1 lead wire is red, whereas 3 is black.
w2. Connect "+" of the tester to fan motor connector's 1 lead
wire, and "-" to 3 lead wire, otherwise the resistance cannot be
measured properly.
No
Replace the indoor electronic control
P.C. board and the indoor fan motor.
Yes
Is the resistance
approx. 4"?
Yes
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
Replace the indoor electronic control P.C. board
and the indoor fan motor.