Mitsubishi Electric MSZ-FA25VA Service Manual page 23

The unit does not operate with the remote controller.
Also, POWER 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, vane motor
connector CN151 front panel driving motor connector
CN1U1 and the i-see Sensor motor connector CN110
from the indoor electronic control P.C. board and turn
ON the power supply.
Does the unit operate with the remote controller?
Does POWER 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
CN211
Varistor(NR11)
CN201
Fuse(F11)
Measure the resistance of the front panel
driving motor coil.
Refer to 9-5.
Measure the resistance of the i-see Sensor
motor coil.
Refer to 9-5.
Yes
Measure the resistance between CN211 3
and 4 of the indoor fan motor connector.
Measure the resistance of the horizontal vane
motor coil and the vertical vane motor coil.
Refer to 9-5.
Replace the varistor(NR11) and fuse(F11).
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
or more?
Replace the fuse (F11).
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
1M"
Replace the fuse (F11) and the indoor fan motor.
Yes
Is the resistance
approx. 4"?
Yes
Replace the indoor electronic control P.C. board.
23
Short/open circuit:
Replace the front panel driving motor
and the indoor electronic control P.C.
board.
Short/open circuit:
Replace the i-see Sensor motor and the
indoor electronic control P.C. board.
Short/open circuit:
Replace the indoor fan motor.
Short/open circuit:
Replace the horizontal vane motor, the
vertical vane motor and the indoor
electronic control P.C. board.
No
Replace the indoor electronic control P.C. board
and the indoor fan motor.