With regular maintenance, both AC induction motors and DC electric motors can deliver years of reliable service. However, even the best-maintained motors eventually face failures due to wear, electrical issues, or improper application.
Read Our Blog: AC vs. Dc Motors
Whether you just received a brand-new motor that refuses to start or an old reliable unit finally shut down your production line, knowing the most common electric motor problems and solutions can save you time, money, and downtime.
At Square One Electric Motors & Pumps, we help facilities across Delaware, Pennsylvania, New Jersey, and Maryland diagnose issues, rewind motors, and supply fast replacement units when needed.
Essential Electric Motor Safety Tips Before Troubleshooting
Before attempting any type of motor repair, safety must come first. Follow these industry-standard precautions:
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Disconnect Power – Always cut power before performing maintenance.
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Discharge Capacitors – Capacitors hold dangerous charges even when motors are off.
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Avoid Loose Clothing – Keep hands, clothing, and tools away from moving parts.
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Replace Safety Guards – Never operate without all guards properly installed.
Common AC Induction Motor Problems & Solutions
AC induction motors are the backbone of HVAC systems, pumps, conveyors, and manufacturing machinery. Below are 11 issues you may encounter and recommended steps to troubleshoot.
1. Motor Fails to Start Upon Installation
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Possible Cause: Miswired connections → Verify motor wiring against the manufacturer’s schematic.
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Possible Cause: Rotor striking stator or bent fan guard → Reassemble motor or replace damaged parts.
2. Motor Runs, Then Fails to Restart
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Tripped breaker or blown fuse → Reset/replace.
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Shorted stator → Inspect windings; repair or rewind.
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Overload/jammed load → Inspect load for obstructions.
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Failed capacitor (single-phase) → Test with ohmmeter and replace.
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Defective starting switch → Inspect centrifugal switch and replace if damaged.
3. Motor Runs but Dies Down
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Voltage drop → Check supply; contact power company if below 90% of rating.
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Increased load → Verify airflow or equipment changes.
4. Motor Takes Too Long to Accelerate
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Bad capacitor or switch → Test and replace.
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Bearing failure → Replace noisy or rough bearings.
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Low voltage → Confirm supply within 10% of rating.
5. Motor Runs in the Wrong Direction
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Incorrect wiring → Reconnect according to wiring diagram.
6. Motor Overload Protector Trips
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Load too high → Verify load matches motor rating.
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High ambient temperature → Improve cooling airflow.
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Defective protector → Replace with correct rating.
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Grounded winding → Inspect and rewind if necessary.
7. Motor Vibrates
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Misaligned load → Realign motor and driven equipment.
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Out-of-balance load → Test motor shaft runout.
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Defective bearings → Replace bearings; re-grease if applicable.
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Rotor imbalance or excess endplay → Rebalance or shim bearings.
8. Bearings Continuously Fail
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Excessive or uneven load → Inspect belt tension and load balance.
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High operating temperature → Switch to high-temperature grease.
- Read our Blog: Common Bearing Failures
9. Grinding Noise at Startup
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Rotor striking stator → Inspect for shipping damage, realign end bells, or replace motor.
10. Start Capacitors Keep Failing
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Motor not reaching speed quickly enough → Check duty cycle; replace with higher voltage capacitor.
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Too many start cycles → Limit starts to manufacturer’s recommendation.
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Low voltage → Verify supply.
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Defective switch → Replace starting switch.
11. Run Capacitor Failure
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Ambient temperature too high → Improve cooling conditions.
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Surge damage (lightning, voltage spikes) → Install surge protector.
Common DC Electric Motor Problems & Solutions
DC motors power conveyors, hoists, and many industrial systems where speed control is essential. Here are the top 6 DC motor problems to watch for:
1. Motor Won’t Start on Installation
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Miswired motor → Double-check wiring.
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No controller output → Test voltage supply.
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Fan guard rubbing → Replace guard.
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Armature rubbing magnets → Realign or replace motor.
2. Motor Stops After Running
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Blown fuse/tripped breaker → Replace/reset.
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Shorted armature → Inspect commutator and test continuity.
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Worn brushes → Replace brushes per manufacturer guidelines.
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Defective controller → Check output voltage.
3. Motor Runs but Loses Power
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Increased load → Compare amp draw to nameplate rating.
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Controller settings incorrect → Adjust torque or IR compensation.
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Open connection → Inspect wiring and armature.
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Worn or unseated brushes → Inspect and replace.
4. Motor Accelerates Too Slowly
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Controller accel trim needs adjustment.
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Worn brushes → Replace.
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Defective bearings → Inspect and replace.
5. Motor Runs in the Wrong Direction
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Incorrect wiring → Swap two motor leads.
6. Clicking Noise During Operation
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Burr on commutator → Smooth surface with commutator stone.
🏆 Troubleshooting by Motor Brand
Following is a list of troubleshooting & maintenance tips by manufacturer:
🔹 ABB Baldor Motor Installation & Maintenance Tips
One of the most recognized names in the industry, Baldor motors are known for their energy efficiency, reliability, and wide application range. From general purpose to severe duty, Baldor offers motors that meet or exceed NEMA Premium® efficiency standards.
Click for Baldor Manuals & Downloads
🔹 Teco Westinghouse
Producer of top-notch machinery for pumps, fans, compressors, rolling mills, grinders, crushers, and various rugged applications. Motors are used in petroleum, chemical, pulp, paper, mining, marine propulsion, steel, electric utility, agriculture, and global industries.
Click for Teco Westinghouse Manuals & Brochures
Shop Teco Westinghouse Motors Online
🔹 US Motors
US Motors, a division of Emerson Electric, was acquired in 2010 by Nidec Motor Corporation, but many motors still bear the US Emerson name. US Motors offers industrial and commercial electrical motors for HVAC, pump, swimming pool, agriculture, and severe duty applications, and more.
Click for US Motors Technical Data & Maintenance
🔹 Leeson Electric Motors
Leeson produces a vast selection of single-phase, three-phase, and DC motors designed for applications ranging from agriculture and manufacturing to HVAC and food processing. Their motors are highly valued for versatility and dependable service life.
Read Basic Troubleshooting for Rotating Equipment
🔹 Marathon Electric Motors
Marathon is a trusted name in industrial and commercial motor design. Known for their Blue Chip Series®, these motors are ideal for demanding environments, ensuring rugged performance in HVAC, pumping, and processing systems.
🔹 Century (Regal Rexnord)
Century motors are widely used in HVAC, pool & spa, and agricultural applications. With efficient designs and durable enclosures, Century offers reliable operation and lower energy consumption across multiple industries.
Click here for Century Motor User Manuals
🔹 Worldwide Electric Motors
Worldwide Electric offers a comprehensive line of general purpose, severe duty, and specialty motors at competitive prices, making them a popular choice for facilities looking to balance cost with performance.
Worldwide AC Motor Installation, Operation, & Maintenance Manual
🔹 Elektrim Motors
Elektrim IEC motors are well known for precision engineering and European design standards. Ideal for OEMs and international projects, these motors deliver reliable performance with metric dimensions and global compatibility.
🔹 Lincoln Electric Motors
Lincoln motors are engineered for durability, performance, and energy efficiency. They’re especially strong in three-phase industrial applications and provide a cost-effective solution without sacrificing quality.
✅ Every motor we sell is brand-new, ships fast from the nearest warehouse, and includes the full manufacturer’s warranty.
🛠️ Professional Motor Repair Services in Delaware & Beyond
Sometimes troubleshooting is not enough. If your AC or DC motor has major winding, rotor, or mechanical damage, professional repair or replacement is the best option.
At Square One Electric Motors & Pumps, we offer:
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Motor rewinds up to 2,500 HP
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Bearing replacement and shaft repairs
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Oven drying for moisture-damaged motors
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Machine shop services for precision alignment
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On-site emergency support
We are an authorized warranty repair center for leading motor manufacturers. Take a look at our Linecard to see more details.
📞 Contact us today for expert motor repair or to order a replacement.
📚 Related Blog Posts
For deeper knowledge on motors, maintenance, and applications, explore these helpful resources from our Tech Tips Blog:
✅ Keep Your Motors Running Strong
AC and DC motors are essential to industrial productivity, HVAC efficiency, and facility operations. Understanding common motor failures—from bad capacitors to worn bearings—empowers maintenance teams to act quickly and minimize downtime.
For motors that require professional diagnosis, rewinds, or replacement parts, Square One Electric Motors & Pumps is here to help. With fast shipping, expert service, and access to top brands, we ensure your systems keep moving.
📞 Ready to solve your motor issue? Book an appointment today.