Mitsubishi Electric MSZ-A09NA Service Manual page 19

Indoor unit operates by pressing EMERGENCY OPERATION switch, but does not operate with the remote controller.
Check of remote controller and receiver P.C. board
B
wCheck if the remote controller is exclusive for this air conditioner.
Switch ON the remote controller.
Is LCD display on the the remote
controller visible?
Yes
Remove the batteries, then set them back
and press RESET button. (Refer to 8-1.4.)
Check if the unit operates with the remote
controller.
Does the unit operate with the
remote controller?
Yes
OK
Measure the voltage between receiver P.C. board
connector CN301 No.2(+) and No.3(-) when the
remote controller button is pressed.
Replace the receiver P.C. board.
No
Replace the batteries. (Refer to 8-1.4.)
(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 3.28ft.?
MSZ-A24NA
MSY-A24NA
Is the voltage approx. 4V DC?
No (5V or 0V DC)
Yes
Yes
No
MSZ-A09/12/15/17NA
MSY-A15/17NA
Yes
Replace the indoor electronic control P.C.
board.
19
No
Replace the remote controller.
Reinstall the unit away from lights.
Attach a filter on receiving part.