Mitsubishi Electric Mr.Slim MSZ09UN W, Service Manual, Page: 52 / 77

52
Disconnect the connector between the
compressor and transistor module.
Turn ON the power supply to indoor unit,
and press twice (heating) the
EMERGENCY OPERATION switch.
Measure resistance of the R.V. coil to check if it is defective or not.
If the connector CN 721 is not connected or the R.V. coil is open, the voltage occurs between the terminals even when the control is OFF.
Is there voltage of
208/230V AC
between CN 721
1
and
2
on the relay
P.C. board?
1
CN721
Relay P.C. board
2
R.V. coil
208/230V AC
Yes
No Replace the
relay P.C. board.
Replace the
R.V. coil.
Check of R.V. coil
K
Cooling operates when heating is expected.
Replace the
outdoor fan motor.
Is there voltage of
208/230V AC between
outdoor terminal block(TB1)
L1
and
L2
?
Is there voltage of
approx. 208/230V AC
either between
1
and
3
or between
3
and
5
at
CN 771?
Disconnect the connector CN 771 on the relay P.C.
board.
Disconnect the connector between compressor and
IPM.
Turn ON the power supply to indoor unit and press
the EMERGENCY OPERATION switch.
Yes
Yes
No
CN771
Relay P.C. board
1 2 3
4 5 6
Fan
motor
Power
supply
Outdoor terminal block
L1
N
L2
Replace the
relay P.C. board.
No
Refer to
M
"Check of
power supply." on
page 53.
TB1
Check of outdoor fan motor
L
Outdoor fan motor does not work.
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