Furnace Blower Motor Run Capacitor

6 min read Jun 26, 2024
Furnace Blower Motor Run Capacitor

Furnace Blower Motor Run Capacitor: Understanding Its Importance


A furnace blower motor run capacitor is a crucial component in the heating system of your home. It plays a vital role in ensuring the efficient operation of the blower motor, which is responsible for circulating warm air throughout your home. In this article, we will delve into the world of furnace blower motor run capacitors, exploring their functions, types, and importance in maintaining a comfortable indoor climate.

What is a Furnace Blower Motor Run Capacitor?

A furnace blower motor run capacitor is an electrical component that helps to power the blower motor in your furnace. It is typically a rectangular-shaped device with two or three terminals, designed to store electrical energy and release it as needed to facilitate the motor's operation.

How Does a Furnace Blower Motor Run Capacitor Work?

The capacitor works by storing energy in the form of an electrostatic field between two conductive plates. When the blower motor is turned on, the capacitor discharges its stored energy to provide a boost to the motor, allowing it to start quickly and efficiently. Once the motor is running, the capacitor continues to supply energy to maintain its operation.

Types of Furnace Blower Motor Run Capacitors

There are two main types of furnace blower motor run capacitors:

Single-Phase Capacitors

These capacitors are designed for use in single-phase motors and are typically used in residential furnaces. They are available in various voltage ratings, such as 370V, 440V, and 480V.

Three-Phase Capacitors

These capacitors are used in three-phase motors and are commonly found in commercial or industrial furnaces. They are designed to operate at higher voltage ratings, such as 575V and 690V.

Importance of Furnace Blower Motor Run Capacitors

The furnace blower motor run capacitor is essential for the proper operation of your furnace's blower motor. Here are some reasons why:

Efficient Motor Operation

The capacitor ensures that the blower motor starts quickly and efficiently, reducing the strain on the motor and the furnace's electrical system.

Improved Airflow

By providing a stable and consistent power supply, the capacitor helps to maintain proper airflow throughout your home, ensuring that warm air is circulated evenly.

Increased Motor Life

The capacitor helps to reduce the wear and tear on the blower motor, increasing its lifespan and reducing the need for frequent repairs or replacements.

Energy Savings

By improving the motor's efficiency, the capacitor can help to reduce energy consumption, leading to lower energy bills and a more environmentally friendly heating system.

Common Problems with Furnace Blower Motor Run Capacitors

Like any electrical component, furnace blower motor run capacitors can fail or become damaged over time. Some common problems include:

Capacitor Failure

The capacitor can fail due to voltage surges, overheating, or physical damage, leading to reduced airflow and inefficient motor operation.

Wrong Capacitor Size

Using a capacitor with the wrong voltage rating or capacitance value can cause the motor to malfunction or fail prematurely.

Corrosion or Wear

Corrosion or wear on the capacitor's terminals or internal components can reduce its effectiveness and lead to premature failure.


In conclusion, the furnace blower motor run capacitor is a critical component in the heating system of your home. By understanding its functions, types, and importance, you can ensure that your furnace operates efficiently and effectively, providing a comfortable indoor climate for you and your family. If you suspect a problem with your capacitor, it is essential to consult a qualified HVAC professional for diagnosis and repair.