Mitsubishi Electric MS-18RV-E1 Service Manual page 52

Check of indoor fan motor
A
Indoor fan doesn't operate.
No
Re-connect the lead wires.
Disconnect lead wires from connector CN211 on the indoor electronic control P.C. board.
Measure resistance between lead wires : No.1 and No.4 and then No.1 and No.2(MS-18/24RV)
Check of remote controller and receiver P.C. board
B
Indoor unit operates by pressing the EMERGENCY OPERATION switch, but doesn't operate with the remote controller.
wCheck if the remote controller is exclusive for this air conditioner.
Switch on the remote controller.
Is LCD display on the remote
controller displayed?
Yes
Remove the 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
Turn OFF the power supply.
Check connector CN211 visually.
Are lead wires connected?
: No.1 and No.4 and then No.3 and No.4(MS-30RV).
Is resistance 0 (short circuit) or ∞ (open circuit)?
Repair or replace the indoor fan motor.
No
Replace the batteries.(Refer to page 47.)
(not clear)
Turn on a radio to AM and press switch on
No
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 No.2(+) and No.1 when remote controller button
is pressed.
Is the voltage approx. 4V DC?
Replace the receiver P.C. board.
Yes
Is soldering point of the connector
correctly soldered?
No
Yes ( 0 or ∞ ) (others)
No
Yes
No
No(5V or 0V DC)
52
No
Yes
Insert screwdriver into air outlet to rotate indoor fan
motor slowly for 1 revolution or over, and measure
voltage between No.2(+) and No.3(-) on CN121.
Does voltage repeat 0V DC and 5V DC?
Yes
Replace the indoor electronic control P.C. board.
No
Replace the remote controller.
Yes
Re-install the unit away from lights.
Attach a filter on receiving part.
Yes
Replace the indoor electronic control P.C.
board.
Re-solder it.