Mitsubishi Electric MSZ-JP12WA-U Service Manual page 23

C Check of indoor P.C. board and indoor fan motor
Turn OFF the power supply.
Remove indoor fan motor connector CN211
from indoor power P.C. board 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?
Does OPERATION INDICATOR lamp light
up by pressing the emergency operation
switch?
No
Turn OFF the power supply.
Check both "parts side" and "pattern
side" of the indoor power P.C. board
visually.
*1. The fan motor connector's lead wire is red,
whereas is black.
*2. Connect "+" of the multimeter to fan motor
connector's lead wire, and "-" to
otherwise the resistance cannot be measured
properly.
*3. Please replace the fuse after removing the
indoor power P.C. board from the electrical
box.
Measure the resistance of resistor (R111)
on the indoor power P.C. board.
MSZ-JP09/12NA
Indoor electronic control
P.C. board
Indoor terminal
P.C. board
Indoor power P.C. board
Fuse
(F11)
Varistor
(NR11)
OBH820A
Measure the resistance between
CN211 and
connector.
Measure the resistance of the vane
motor coil.
Yes
(Refer to 9-5.)
Replace the varistor (NR11)
and fuse (F11). *3
Is the varistor (NR11)
burnt and the fuse (F11)
blown?
Be sure to check both the fuse and
the varistor in any case.
Is the fuse (F11) blown
only?
Measure the resistance between
CN211 (+) and
motor connector. *1, *2
lead wire,
Is the resistance 1MΩ or more?
Replace the fuse (F11). *3
JPN (GND)
CN10A
12 V DC
5 V DC
R111
CN211
Replace the indoor electronic control P.C. board.
of the indoor fan motor
Yes
No
No
Yes
(-) of indoor fan
Replace the fuse (F11) and the
No indoor fan motor. *3
Yes
Is there resistance of resistor
(R111) approximately 2 Ω?
Yes
Is there approximately 5 V DC between
5 V (+) and GND (-) of the indoor
electronic control P.C. board? Is there
approximately 9 V to 13 V DC between
12 V (+) and GND (-) of the indoor
electronic control P.C. board?
No
Is the connector CN10A on
the indoor electronic control
P.C. board or lead wires
disconnected?
No
23
Short/ open circuit:
Replace the indoor fan motor.
Short/ open circuit:
Replace the vane motor and the indoor
electronic control P.C. board.
Replace the indoor power
No
P.C. board and the indoor
fan motor and the indoor
terminal P.C. board.
Replace the indoor fan motor.
Yes
Connect the connector CN10A or repair
Yes disconnection.