Check Of Remote Controller And Receiver P.c. Board; Check Of Indoor Electronic Control P.c. Board - Mitsubishi Electric MSZ-CA25VB Service Manual

Indoor unit operates by pressing the 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 9-1.4.)
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.

Check of indoor electronic control P.C. board

C
Check both "parts side" and "pattern side" of the
indoor electronic control P.C. board visually.
Turn OFF the power supply.
Disconnect 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 or
does OPERATION INDICATOR lamp light up
by pressing EMERGENCY OPERATION switch?
Yes
Replace the vane motor.
Turn OFF the
power supply.
Is winding resistance
of vane motor 0 "?
Is winding resistance
of fan motor 0 "?
Replace the fan motor.
No
Replace the batteries.(Refer to 9-1.4.)
(not clear)
No
Turn on a radio to AM and press switch on
the remote controller.
Is noise heard from the 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 receiver P.C. board.
Fuse (F11)
Indoor electronic
No
control P.C. board
Turn OFF the
power supply.
Yes
No
No
Yes
No
Yes
Yes
No
Yes
No(5V or 0V DC)
Varistor (NR11)
Indoor electronic
control P.C. board
1
3
CN201
Replace the fuse.
Yes
Is fuse (F11) blown?
No
No
Is varistor (NR11) burnt?
Yes
Replace the varistor.
18
Indoor electronic control
P.C. board
3
1 2
CN125
Power monitor
receiver P.C. 1 2 5 4 3
board
CN302
Remote
controller
Replace the remote controller.
Reinstall the unit away from lights.
Attach a filter on receiving part.
Replace the indoor electronic control P.C.
board.
Thermal fuse connector
F12
N
2
3
Terminal
Replace the indoor
block
electronic control
P.C. board.
Measure the
resistance
between
1
CN201 on
the indoor
Is resistance approx. 0"?
electronic control
N
P.C. board and
on the terminal
block with the
Replace the fuse (F12).
tester.
1
CN109
Yes
No (∞)