Check Of Indoor Electronic Control P.c. Board; Check Of Outdoor Thermistors - Mitsubishi Electric Mr.Slim MSZ09UN Service Manual

The unit doesn't operate with the remote controller.
Also, the OPERATION INDICATOR lamp doesn't light up by pressing the EMERGENCY OPERATION switch.

Check of indoor electronic control P.C. board

I
Check the both "parts side" and "pattern
side" of indoor electronic control P.C.
board visually.
Turn OFF the power supply.
Disconnect indoor fan motor connector CN211(MSZ09UN)
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 or
the OPERATION INDICATOR lamp light up
by pressing the EMERGENCY OPERATION switch?
Yes
Turn OFF the
Replace the vane
power supply.
motor.
Is winding
resistance of
vane motor 0 "?
Be sure to check both resistances.
Is winding
resistance of
fan motor 0 "?
Replace the fan
motor.
When OPERATION INDICATOR lamp flashes 6-time.
The thermistors in the outdoor unit are abnormal.

Check of outdoor thermistors

J
Disconnect the connectors CN641 and CN642 from the outdoor electronic control P.C. board.
Check the characteristics of each thermistor.
( )
Defrost
thermistor
RT61
Measure
resistance
between CN
6411 and 2.
( Discharge )
temperature
thermistor
RT62
Measure
Does the
resistance resistance of the
thermistor have
between CN
the characteristics
6413 and 4.
on page 45?
Fin
(
)
temperature
thermistor
RT64
Measure
resistance
between CN
6421 and 2.
No
Turn OFF the
power supply.
Yes
No
Be sure to check both fuse
and varistor in any case.
No
Yes
1 Connect CN641 and
2 Disconnect the
Yes
No
Replace the
thermistor.
Replace the fuse.
Yes
No
Is fuse(F11) blown?
No
Is varistor(NR11) burnt?
Yes
Replace the varistor.
CN642.
connector between
the compressor and
IPM. Replace the outdoor
electronic control
P.C. board.
Turn ON the
power supply to
indoor unit and Does the unit
press the operate 10 minutes
or more?
EMERGENCY
OPERATION
switch.
Is LED in the
outdoor electronic
control P.C. board
flashing 5 minutes?
Reconnect the
connector.
51
Replace the indoor
electronic control
P.C. board.
No
Yes
Yes
No