Mitsubishi Electric MCF-GA50VB-E1 Service Manual page 13

Indoor unit operates by pressing the EMERGENCY OPERATION switch, but does not operate with the remote con-
troller.
Check of remote controller and receiver P.C. board
B
w Check if the remote controller is exclusive for this air conditioner.
Switch on the remote controller
Is LCD display on remote controller
visible?
Yes
Remove batteries and then set them back and press
the RESET button. Check if the unit operates with
remote controller.
Does the unit operate with remote controller?
Yes
OK
Is noise heard from radio?
Yes
Are there any fluorescent lights
of inverter or rapid-start type
within the range of 1m?
No
Measure the voltage between receiver P.C.board connector No.2(+)and No.1 when remote controller button is pressed.
No
Is the voltage approx. 4V DC?
No
(5V DC or 0V DC)
Replace the receiver.
The unit doesn't operate with the remote controller.
Also, the OPERATION INDICATOR lamp doesn't light up by pressing the EMERGENCY OPERATION switch.
Check of indoor electronic control P.C. board
C
Check both "parts side"and "pattern
side" of indoor electronic control P.C.
board visually.
No
Replace the batteries.(Refer to 9-1.)
(not clear)
No
Turn on a radio to AM and press
switch on remote controller.
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 fuse.
Yes
Is fuse(F11)blown?
Be sure to check both fuse
and varistor in any case.
Is varistor(NR11)burnt?
Yes
Replace the varistor.
13
No
Trouble of the indoor electronic
control P.C. board.
No