24
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 EMERGENCY OPERATION
switch?
Yes
No
Measure the resistance of indoor fan
motor.
(Refer to 9-6 .)
Short/ open circuit:
Replace the indoor fan motor.
Turn OFF the power supply.
Check both “parts side” and “pattern
side” of the indoor power P.C. board
visually.
Replace the varistor (NR11)
and fuse (F11). 3
Is the varistor (NR11)
burnt and the fuse (F11)
blown?
No
No
Yes
Yes
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 (-) of indoor fan
motor connector. 1, 2
Yes
Is the resistance 1M
or more?
Replace the fuse (F11) and the
indoor fan motor. 3
No
Replace the fuse (F11). 3
Measure the resistance of resistor (R111)
on the indoor power P.C. board.
No
No
Replace the indoor power
P.C. board and the indoor
fan motor [and the indoor
terminal P.C. board (
MSZ-
HM09/12/15NA
)].
Replace the indoor electronic control P.C. board.
Measure the resistance of the vane
motor coil.
(Refer to 9-5.)
Short/ open circuit:
Replace the vane motor and the indoor
electronic control P.C. board.
1. The fan motor connector's lead wire is red,
whereas is black.
2. Connect "+" of the tester to fan motor
connector's lead wire, and “-” to lead wire,
otherwise the resistance cannot be measured
properly.
3. Please replace the fuse after removing the
indoor power P.C. board from the electrical
box.
Is there approximately 5 VDC between
5 V (+) and GND (-) of the indoor
electronic control P.C. board? Is there
approximately 9 V to 13 VDC between
12 V (+) and GND (-) of the indoor
electronic control P.C. board?
Is the connector CN10A on
the indoor electronic control
P.C. board or lead wires
disconnected?
Yes
Replace the indoor fan motor.
Yes
Connect the connector CN10A or repair
disconnection.
No
Yes
Indoor electronic control
P.C. board
GND
CN10A
12 VDC
5 VDC
Is there resistance of resistor
(R111) approximately 4
?
Indoor power P.C. board
CN211
R111
C Check of indoor P.C. board and indoor fan motor
MSZ-HM18/24NA
MSZ-HM09/12/15NA
JPN (GND)
CN10A
12 VDC
5 VDC
Indoor electronic control
P.C. board
Indoor power P.C. board
R111
CN211
Indoor terminal
P.C. board
Fuse
(F11)
Varistor
(NR11)
OBH746B
