Mitsubishi Electric MSC-A07YV-E1 Service Manual page 23

Indoor unit operates by pressing the EMERGENCY OPERATION switch, but doesn't operate with the remote controller.
B B Check of remote controller and receiver P.C. board
wCheck the remote controller is exclusive for this air conditioner.
Switch on the remote controller.
Is LCD display on the remote con-
troller displayed?
Yes
Remove batteries, then set them back and press the RESET
button. Check if the unit operates with the remote controller.
Does the unit operate with the
remote controller?
Yes
OK
The unit doesn't operate with the remote controller.
Also, the OPERATION INDICATOR lamp doesn't light up by pressing the EMERGENCY OPERATION switch.
C C Check of indoor electronic control P.C. board
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
Turn OFF the
Replace the vane
power supply.
motor.
Be sure to check both resistances.
Replace the fan motor.
No
Replace the batteries. (Refer to page 19.)
(not clear)
No
Turn on a radio to AM and press switch
on the remote controller.
Is noise heard from radio?
Are there any fluorescent lights of
inverter or rapid-start type within
the range of 1m?
Measure the voltage between receiver P.C. board connector CN302
(+)
(–)
No.3 and No.5 when the remote controller button is pressed.
Is the voltage approx. 4V DC?
Replace the power monitor, receiver P.C. board.
No
Turn OFF the
power supply.
Yes
Is winding
No
resistance of
vane motor 0 "?
Is winding
No
resistance of
fan motor 0 "?
Yes
Yes
No
No(5V or 0V DC)
Replace the fuse.
Yes
No
Is fuse (F11) blown?
Be sure to check both fuse
and varistor in any case.
No
Is varistor (NR11) burnt?
Yes
Replace the varistor.
23
No
Replace the remote controller.
Yes
• Reinstall the unit away from lights.
• Attach a filter on receiving part.
Yes
Replace the indoor electronic control
P.C. board.
Replace the indoor
electronic control
P.C. board.