Electric Motor Run Capacitor Failure Symptoms

4 min read Jun 26, 2024
Electric Motor Run Capacitor Failure Symptoms

Electric Motor Run Capacitor Failure Symptoms

An electric motor run capacitor is a crucial component in many electrical systems, including air conditioners, refrigerators, and washing machines. Its primary function is to store energy and provide a boost to the motor during startup and operation. However, like any other electrical component, the run capacitor can fail, leading to various problems and symptoms. In this article, we will explore the common symptoms of electric motor run capacitor failure.

Motor Won't Start or Runs Slowly

One of the most obvious symptoms of a failed run capacitor is a motor that won't start or runs slowly. When the capacitor fails, the motor may struggle to turn or may not turn at all. This is because the capacitor provides the necessary energy to the motor to overcome the initial startup resistance.


A failing run capacitor can cause the motor to overheat, leading to a significant reduction in its lifespan. When the capacitor is not functioning properly, the motor has to work harder to generate power, resulting in increased heat generation.

Vibrations and Noise

A faulty run capacitor can cause the motor to vibrate excessively, leading to noise and premature wear on the motor bearings. This is because the capacitor helps to smooth out the motor's rotation, and when it fails, the motor's rotation becomes uneven.

Reduced Efficiency

A failed run capacitor can reduce the motor's efficiency, causing it to consume more power than usual. This can lead to increased energy bills and a reduction in the motor's overall performance.

Tripped Circuit Breakers

In some cases, a failing run capacitor can cause the circuit breaker to trip frequently. This is because the capacitor's failure can cause the motor to draw excessive current, leading to an overload on the circuit.

Capacitor Swelling or Leaking

A visual inspection of the capacitor can reveal signs of failure, such as swelling or leaking. A swollen capacitor is a clear indication of a failure, and it should be replaced immediately to prevent further damage.

Burning Smell

A burning smell from the motor or capacitor is a strong indication of a failure. This smell can be a result of the capacitor's insulation breaking down, causing the component to overheat and release a burning odor.


A faulty run capacitor can cause a range of problems, from reduced motor performance to complete motor failure. It is essential to monitor the motor's performance and look out for the symptoms mentioned above. If you suspect a run capacitor failure, it is recommended to replace the capacitor as soon as possible to prevent further damage to the motor and other electrical components.