Mitsubishi Electric MUFZ-KJ-NAHZ Series Service Manual page 29

Check of remote controller, display receiver P.C. board and indoor control P.C. board
B
Check if the remote controller is exclusive for this air conditioner.
Press STOP/OPERATE (OFF/ON)
button on the remote controller.
Is LCD display on the remote
controller visible?
Yes
Remove the batteries, then set them
back and press RESET button.
(Refer to 9-1.4.)
Check if the unit operates with the
remote controller.
Does the unit operate with the
remote controller?
Yes
OK
Replace the batteries. (Refer to 9-1.4.)
No
(Not clear)
Assign a number of remote controller.
(Refer to 7-2.)
Check if the unit operates with the
No
remote controller.
Does the unit operate with
the remote controller ?
Yes
OK
Measure the voltage between display receiver P.C. board connector CN301
when the remote controller button is pressed.
Is the voltage approximately 4 VDC - 5 VDC?
Replace the display receiver P.C. board.
1 Look at the image of the signal transmitting section of
the remote controller through the monitor of a digital
camera or a camera phone. It is normal if the LED of
the signal transmitting section lights up when the STOP/
OPERATE (OFF/ON) button on the remote control-
ler is pressed. However, it may be dif cult to see the
illuminated LED of the signal transmitting section with a
smartphone camera.
2 If the inverter uorescent light is turned on when the
room is cool, the unit may have dif culty receiving the
signal from the remote controller or may not be able to
operate with it; if the inverter uorescent light is turned
on when the room is warm, the unit may be able to
operate with the remote controller.
Turn ON a radio to AM and press
STOP/OPERATE (OFF/ON) button
No
on the remote controller. 1
Is noise heard from radio?
Yes
Are there any uorescent lights of
inverter or rapid-start type within
the range of 3.28 ft. (1 m)?
No
Yes
No
29
Replace the remote controller.
No
• Reinstall the unit away from lights.
• Attach a lter on receiving part.
Yes
2
(+) and (-)
Replace the indoor electronic
control P.C. board.