Mitsubishi Electric MS-09SN-C1 Service Manual page 37

When OPERATION INDICATOR lamp flashes 3-time.
Indoor fan motor doesn't operate.
Check of indoor fan motor
A
No
Are lead wires connected?
Re-connect the lead wires.
Disconnect lead wires from connector CN211 on indoor electronic control P.C. board.
Measure resistance between lead wires
Indoor unit operates by pressing the EMERGENCY OPERATION switch, but does not operate
with the remote controller.
Check of remote controller and power monitor, receiver P.C. board
B
Switch on the remote controller.
Is LCD display on the remote con-
troller 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
No (MS-09/10SN)
Replace the indoor electronic control P.C.
board with power monitor, receiver P.C. board.
Turn OFF the power supply.
Check connector CN211 visually.
Yes
No.1 and No.3 and then No.2 and No.3(MS-09/10SN)
{
No.1 and No.4 and then No.1 and No.2(MS-12/15/17/18/24SN)
Is resistance 0 (short circuit) or ∞ (open circuit)?
Repair the indoor fan motor.
Replace the indoor electronic control P.C. board.
No
Replace the batteries.(Refer to page 34.)
(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 indoor receiver P.C. board connector No.2
No.1 when remote controller button is pressed.
Is the voltage approx. 4V DC?
Replace the receiver P.C. board.
Is soldered point of connector normal?
(others)
Yes ( 0 or ∞ )
w Check the remote controller is exclusive
for this air conditioner.
w In case of replacing the receiver P.C.
board of MS-09SN or MS-10SN replace
the indoor electronic control P.C. board
with it because they are unified.
No
Yes
Yes
No
(MS-12/15/17/18/24SN)
Yes
No(5V or 0V DC)
37
Yes
Re-solder it.
}
Insert screwdriver into air outlet to
rotate indoor fan motor slowly for 1
revolution or over, and measure
No
voltage between YLW and GRY of
CN121.
No
Does voltage repeat 0V
DC and more than 5V?
Yes
Replace the remote controller.
• Re-install the unit away from lights.
• Attach a filter on receiving part.
(+)
and
Replace the indoor electronic control P.C.
board.
No