Check Of Indoor Fan Motor; Check Of Remote Controller And Receiver P.c. Board - Mitsubishi Electric MSH-18RV Service Manual

Check of indoor fan motor

A
Indoor fan motor doesn't operate.
No
Are lead wires connected?
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(MSH-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 con-
troller.
w Check 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 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.
Yes
{
No.3 and No.4 and then No.1 and No.4(MSH-30RV).
Is resistance 0 (short circuit) or ∞ (open circuit)?
Yes ( 0 or ∞ )
Repair or replace the indoor fan motor.
No
Replace the batteries.(Refer to page 52.)
(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 1m?
Measure the voltage between receiver P.C. board connector No.2(+) and No.1 (MSH-18RV) / CN301 No.2(+)
and No.3(-) (MSH-24/30RV) when the remote controller button is pressed.
Is the voltage approx. 4V DC?
Replace the receiver P.C. board.
Is soldered point normal?
Yes
Insert screwdriver into air outlet to rotate indoor fan
motor slowly for 1 revolution or over, and measure
No voltage between No.2(+) and No.3(-) on CN121.
(others)
No
Replace the indoor electronic control P.C. board.
No
Yes
Yes
No
Yes
No(5V or 0V DC)
59
No
Re-solder it.
Does voltage repeat 0V DC and 5V DC?
Yes
Replace the remote controller.
Re-install the unit away from lights.
Attach a filter on receiving part.
Replace the indoor electronic control P.C.
board.