Check Of Indoor Electronic Control P.c. Board - Mitsubishi MSH-A18WV Service Manual

The unit doesn't operate with the remote controller. Also, the OPERATION INDICATOR lamp doesn't light up by press-
ing the EMERGENCY OPERATION switch.

Check of indoor electronic control P.C. board

C
Check the both "parts side" and "pattern
side" of indoor electronic control P.C.
board visually.
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 the OPERATION INDICATOR lamp light up
by pressing the EMERGENCY OPERATION switch?
Yes
Replace the vane
Turn OFF the
motor.
power supply.
Is winding
resistance of
vane motor 0 "?
Be sure to check both resistance.
Is winding
resistance of
fan motor 0 "?
Replace the fan
motor.
No
Turn OFF the
power supply.
Yes
No Is fuse(F11) blown?
Be sure to check both fuse
and varistor in any case.
Is varistor(NR11) burnt?
No
Yes
Replace the varistor.
Fuse (F11)
Indoor electronic
control P.C. board
Replace the fuse.
Yes
No
No
Yes
25
Varistor (NR11)
Replace the indoor
electronic control
P.C. board.