54
MWM-J-2009 Troubleshooting
By means of diagnostic fl ow chart:
Generally, there are two kinds of problems, i.e. starting failure and insuffi cient cooling/heating. “Starting failure”
is caused by electrical defect while improper application or defects in refrigerant circuit causes “Insuffi cient
cooling / heating”.
i ) Diagnosis of Electric circuit
: Faulty : Check : Cause : Remedy
No cooling/heating (Unit fails to start)
No voltage or low voltage
Wrong phase/missing
phase (applicable to 3
phase model)
Components shorted
Connections loose
High or low voltage
Wrong phase/missing
phase (applicable to 3
phase model)
Faulty
Blown
Tripped
Coil burned
Contact faulty
Faulty
Faulty fan motor
Defective operation switch
Evaporator
fan contactor
Over current
relay for
evaporator
fan
Fuse for
operation
circuit
Unit power
supply
Condenser
fan motor
Evaporator
fan motor
Over current
relay for
condenser
fan
Running
21
No voltage or low voltage
Wrong phase/missing
phase (applicable to 3
phase model)
Tripped
Get the right voltage
Repair the power line
Repair or replace the components
Tighten the connections
Get the right voltage
Check the power supply to the
motor: repair when necessary
Change the contactor
Repair or change the motor
Repair the contacts
Repair or change the switch
Get the right voltage
Check the power supply to the
motor: repair when necessary
Stop
Running
Stop
Catalog.indb 54Catalog.indb 54 3/2/2009 4:41:31 PM3/2/2009 4:41:31 PM
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