The biggest challenge, from a service standpoint, is that motors typically spend their working lives unseen, either covered or installed in an enclosed area, such as inside a furnace. A lot of mischief can take place away from watchful eyes, and the knowledgeable service technician must be prepared to go beyond treating the most obvious cause of motor problems.
For example, I’ve pointed out how materials such as lint, sawdust, and other contaminants can build up on the motor’s frame and reduce heat dissipation. These insulating materials often are attracted by the frame’s surface coating or by lubricating oil used in the application.
The vent slots in the frame are easily clogged, cutting down the amount of cooling air that flows over the motor. Even a relatively thin layer of dirt can decrease the motor’s ability to dissipate heat, and as little as a 1 to 2 degree F rise in motor temperature can accelerate the problem.
Many inexperienced service technicians, however, limit their cleanup to just the motor itself. That’s good, but it still represents treating just half of the patient’s symptoms.
Use clear water to remove any accumulated salts from the motor, the shaft, and the surrounding enclosure. For more corroded areas, a wire brush and commercially available cleansers will do the job.
Always check to make sure brackets and metal enclosures are still sound and haven’t been compromised by corrosion. If you suspect any problem, replace the component.
The next big factor is chemical contamination. Many motors work in environments where they are subjected to caustic or corrosive chemicals. These include swimming pools, air conditioning equipment, gate openers, and others.
Salts are the major culprits, followed by water chlorinating compounds, acids dissolved in rain water, cleaners and degreasers, and many others. These insidious materials override the motor’s defenses by contaminating the anticorrosive materials applied to the motor’s frame, shaft, and windings.
In short, as long as you’re cleaning, it’s good practice to police the entire area around the motor.
Keeping a motor clean and cool is an important part of the HVACR service process, but it’s equally important to pay attention to the many components surrounding the motor. Maintain a clean working environment and you’ll be rewarded with longer motor service life, fewer emergency replacements, and happier customers.
Simon, The News’ Motor Doctor, is with A.O. Smith Corp., P.O. Box 245010, Milwaukee, WI 53224-9510.
Publication date: 01/13/2003