A Little Motor Quiz

June 28, 2004
Air conditioning and refrigeration systems rely on blower motors to circulate conditioned air into the living space, refrigerated space, and over the condensing coils. Motor knowledge is a significant weapon in the service technician's arsenal, whether for planned maintenance or emergency repairs.

The next Tech Tips columns will focus on typical motor problems, their causes, and possible solutions. Before we plunge ahead, however, take this brief motor quiz.

True or false: Maintenance plays a small role in motor failures.

True: Today's motors are relatively maintenance free. However, some maintenance (like removing dirt from vent holes and the motor exterior) can extend motor life.

True or false: Newer motors are more likely to break down than older ones.

False: Motors, like anything mechanical, have a finite life. The newer the motor, the more life it should have left. Newer designed motors also have the benefit of the latest refinements in materials and computer-aided design. The only exception to this rule is very old motors. These motors were built like tanks. They were very heavy and ran very cool. However, they frequently needed relubrication.

True or false: A motor problem can be misdiagnosed as something else.

True: Other devices connected to or driven by the motor can actually be the cause of the problem.

True or false: Exposure to environmental conditions has a major effect on motor operation.

True: Motor life is inversely proportional to ambient temperature and exposure to rain. Even sunlight can indirectly affect motor life.

True or false: None of today's motors need lubrication.

False: Never say never - or none. All motors need lubrication. However, most of today's motors do not need relubrication. If a motor's life can be extended by relubrication, there will be instructions on the nameplate. Know what type of motor you're dealing with!

True or false: System conditions do not affect motor performance.

False: Dirty filters, dirty coils, and low voltage can all affect motor performance.

True or false: Motor operating characteristics always have an impact on system operation.

False: They may not always affect system operation, but an unplanned reduction in motor speed can mean less air passes over surfaces that require heat exchange, including the human being. If less air passes over the coils (hot or cold), this will have a negative impact on system performance/operation. The compressor will have to stay on longer to satisfy the thermostat or, in the worst case, the coils could freeze up.

Which of the following is not a common motor problem:

1. Failure to rotate.

2. Failure to come up to speed or accelerate.

3. Failure to run continuously.

4. Vibration or noise.

5. Overheating.

6. None of the above.

7. All of the above.

No. 7 (all of the above) is correct, but keep in mind that whether or not problems are truly common depends on other factors, such as system conditions, the operating environment, and even the motor's brand. We will examine the possible causes of these problems in coming months.

For more information, click on the Emerson Climate Technologies logo above.