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TM-4120-375-14
COMPRESSOR (CONT.)
LOCATION/ITEM
ACTION
REMARKS
TEST
6. COMPRESSOR MOTOR BURNOUT
Burnout of a compressor motor is indicated by lack of continuity of the
motor windings and the condition of compressor oil, which must be determined
after the compressor has been removed from the refrigeration system.
Causes
of compressor motor burnout include the following:
a.
Low line voltage, which causes motor windings to overheat.
Before burning out completely, the overheated windings cause chemical
breakdown of the refrigerant and the oil to form sludge and other system
contaminate.
b.
Loss of refrigerant.
An inadequate charge of refrigerant gas in the
system reduces the amount of cooling gas within the compressor, resulting
in gradual overheating of the motor and failure of the winding.
c.
High Head Pressure.
High head pressures can be caused by clogged or dirty
condenser coils or screens, or by an inoperative condenser fan.
High head
pressure requires the compressor to work harder, creating additional heat
which ultimately can result in motor burnout.
Poor ventilation around the
condenser, and extremely high ambient temperatures can also cause motor
failures.
d.
Moisture in system.
Leakage of air into the refrigeration system starts
a chain reaction which can result in motor burnout.
Air contains oxygen
and moisture which combine with refrigerant gas to form hydrochloric and
hydrofluoric acids.
These combine with compressor oil to form an acid
sludge which is carried throughout the system, and which attacks the motor
windings, causing short circuits and burnout.
5-88
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