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03TA Service Manual
Compressor Motor Burnout. There are several causes of compressor motor burnout. Some of
these are described below.
1. Low line voltage. A compressor motor is designed to operate within the range of plus or minus
10% of its nameplate voltage. Low voltage requires the motor windings to carry more current at
the same compressor load. When this current gets too high or is applied for an extended period,
the motor windings overheat, resulting in a failure or burnout.
2. Loss of refrigerant. The hermetic compressor motor is maintained at proper operating
temperature by passing cool suction gas over the motor windings. A loss of refrigerant can cause
the winding to overheat resulting in a failure or burnout.
3. High head pressure. The system is designed to operate at 200 psig. Excessive head pressure
adds refrigerating load on the compressor, which can cause the windings to overheat and result in
a failure or burnout.
4. Moisture. Moisture in contact with refrigerant oil and the presence of heat will form
hydrochloric or hydrofluoric acid. The acid will destroy the insulation on the motor winding
causing a short circuit, which can increase motor temperature in excess of 3000°F. This extreme
temperature will also create a sludge or black residue in the system.
5. Mechanical failure. Mechanical failure has been determined as a major cause of motor burnout.
Bearing wear or wipe-out may allow rotor to drag--overheating the windings and burnout.
Whenever there is a compressor failure due to a motor burnout, it is important that the system be
thoroughly cleaned before replacing the damaged compressor or otherwise the new compressor may
also be damaged.
4/2/14
9-15
SERVICE OPERATIONS
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