Mitsubishi Electric Mr.SLIM PU-P71VHA Service Manual page 46

Phenomena
(6) Upward/downward vane perform-
ance fault
(7) Left/right louver performance fault
(8) Though the remote controller dis-
play is normal in cool mode, the
capacity is not enough.
(9) Though the remote controller dis-
play is normal in Heat mode, the
capacity is not enough.
OC379F
Factor
1 When the unit is as follows in the HEAT mode, the
vane is not downward.
(Working of COOL protection function)
• During HEAT preparation
• During defrosting
• During compressor stop
2 When setting the downward vane in the cool/dry
mode, the vane changes to Horizontal position after
1 hour
3 Vane motor does not rotate.
A) Vane motor fault
B) Disconnecting, breaking and contact fault of the
connector
C) Setting to no vane unit
4 Standard position reading fault (Vane motor does not
stop.)
A) Limited switch fault
B) Disconnecting breaking and contact fault of the
connector
Only AC timing motor adopting mode (No limited
switch for stepping motor adopting model)
1 Louver motor fault
2 Disconnecting, breaking and contact fault of the con-
nector
1 Filter clogging (dirt)
2 Heat exchanger clogging (dirt)
3 Air duct short cycle
4 Refrigerant shortage
5 Operation failure in electronic expansion valve
6 Thermistor connection failure
7 Incorrect piping size
8 Piping is too long.
1 Filter clogging (dirt)
2 Heat exchanger clogging (dirt)
3 Air duct short cycle
4 Refrigerant shortage
5 Outdoor unit bypass circuit failure
6 Indoor reverse check valve failure
Reverse check valve failure may cause refrigerant
leakage and restrictor failure.
7 Heat insulator of refrigerant pipes is defective.
8 Malfunction of LEV
9 Loose connection in thermistor
1 Normal operation
2 Normal operation
3 A) Vane motor resistance value check
B) Disconnecting, breaking, and contact
C) Check the setting details by selecting
4 A) Limited switch (LS) conductance check
B) Check the removing of indoor control-
1 Louver motor resistance value check
2 Check the removing of indoor controller
board (CNL) breaking line and contact
fault.
1 Open the grille to check the filter.
Clean the filter and remove dust or dirt
away.
2 Clean the heat exchanger.
Lowering the indoor piping temperature
and intake pressure means clogging in
the heat exchanger.
3 Remove screen in the air duct (air outlet/
intake).
4 Check if gas leaks or not in the piping
joint.
5,6 Check the refrigerant circuit operation
7 Check the piping size.
8 Check the capacity loss characteristic for
the piping length.
1 Open the grille to check the filter.
Clean the filter and remove dust or dirt
away.
2 Clean the heat exchanger.
Rising the indoor piping temperature and
outlet pressure means clogging in the
heat exchanger.
3 Remove screen in the air duct (air outlet/
intake).
4 Check if gas leaks or not in the piping
joint.
5 Operating condition check in the refriger-
ant cycle.
6 Since outlet temperature and indoor heat
exchanger temperature does not rise,
measure the outlet pressure and deter-
mine the countermeasure.
7 Check the heat insulator.
8,9 Check the function of refrigerant circuit.
46
Countermeasure
fault of the connector
Stepping motor adopting model
.... CN6V check
AC timing motor adopting model
.... CNV check
the remote controller function.
Setting check of the indoor controller
board J11~J15 (SW1).
ler board (CN23), breaking line and
contact fault.
status.