Fails to Start
Check of power source.
Check of control switch setting.
Only compressor fails to start.
Drop of power voltage.
Defect of compressor capacitor.
Check capacitor.
Replacement.
Check of circuit breaker and fuse.
Gas leakage of feeler bulb of thermostat
Check of control switch.
Only fan fails to start.
Improper wiring.
Improper thermostat setting 
Defect of fan motor capacitor.
Loose terminal connection.
Irregular motor resistance ( 
).
Irregular motor insulation
( 
). Improper wiring
Replacement of fan motor
Irregular motor resistance (
)
Irregular motor insulation ( 
)
Replacement of compressor (Motor damaged)
Regular but fails to start
Replacement of compressor (locking of rotor, metal)