How Does A Furnace Blower Work? Good To Know


Rima Chatterjee

How Does A Furnace Blower Work? Ever wondered how the warm air gets around your house when you switch on the furnace? It’s all thanks to the furnace blower motor. 

In this blog post, we will know the working of a furnace blower in detail.

Furnace Blower Motor


How Does A Furnace Blower Work

The furnace blower/furnace blower motor is a component responsible for rotating the fan blades to draw air into the furnace and push it out through the air ducts. 

Furnace blower motors are essential components of heating and cooling systems. But over time, they might have problems like 

  • Friction
  • Moisture damage
  • Capacitor failure

This can reduce their life expectancy, resulting in reduced airflow and energy efficiency

Signs of a malfunctioning furnace blower include odd noises from the unit or air vents not blowing warm or cooled air.

Components and Parts of Furnace Blower Motor


To understand the working of your furnace blower, you need to get familiar with all the components and parts that make up the system. 

Fan Blades or Blower Wheel

Dirty fan blades can decrease airflow by up to 10%, so maintenance is a must.

  • Axial fan blades range from small to large sizes with metal or plastic materials. 
  • Bifurcated fan blades also vary from small to large sizes with metal or plastic materials. 
  • These blades are designed for high volume airflow or high static pressure applications.

Fan Cage or Squirrel Cage

The fan cage, also known as the squirrel cage, is a crucial part of the furnace blower motor. 

It has many curved blades that spin quickly, creating air pressure that forces hot or cold air through ducts. 

Let’s learn more about this amazing part of the furnace blower motor.

  • The fan cage contains lots of blades shaped like backward-curving hamster wheels.
  • It is crafted from strong materials such as metal or plastic for long-lasting use.
  • Blades whirl around a shaft in the center of the fan cage.
  • Its tiny size and design make it ideal in tight spaces; it creates powerful airflow despite its size.
  • The fan cage helps save money on energy by improving heat transfer and reducing energy use.
  • It is also found in air conditioners and ventilation systems.

Drive Belt Vs. Direct Drive

Let us see the difference between drive belts and direct drive in detail.

Here’s all you need to know,

Drive BeltDirect Drive
Uses a belt & pulley system.Motor is directly attached to the wheel.
Quieter operation.Makes more noise due to contact.
May require occasional belt replacement or adjustment.No belts to replace or adjust.

Capacitor

Capacitors have a variety of functions. There’s the start capacitor, which gives a boost to overcome inertia. 

The run capacitor helps maintain a constant speed while the motor is running. The dual capacitor combines both these functions into one unit. The oil-filled capacitor is used in high temperature applications to prevent overheating.

Types of Furnace Blower Motors


The single-speed blower motor has one speed setting, while the multi-speed blower motor can run at different speeds. 

Single speed blowers are cost-effective and reliable compared to other options. They offer good performance and are easy to service.

On the other hand, the variable speed blower motor can adjust its speed automatically, based on the HVAC system’s temperature demands. 

There are 3 types of blower motors: 

  • Single-speed 
  • Multi-speed
  • Variable speed

Let’s dive deeper to understand each type’s features and benefits.

Single-Speed Blower Motor

A single speed blower motor is a common type of furnace blower motor, used in homes and businesses. It runs at a fixed speed, meaning it provides constant airflow. 

Let’s check out its features and benefits.

Voltage Requirements115-230 volts AC.
Air Flow Rate400-600 cubic feet per minute (CFM).
MaintenanceLow, as it has fewer moving parts and doesn’t need lubrication.

Multi-Speed Blower Motor

A multi-speed blower motor is a special type of furnace blower motor that can adjust the airflow.

This motor can adjust the speed to give you just the right amount of airflow. It’s great for energy savings and noise reduction, plus it extends the life of other parts. 

Also, you can set the motor to lower speeds during regular use and higher speeds during peak heating or cooling times.

It’s important for HVAC systems to be efficient and perform well. Here’s how it works:

SpeedRPMAmperage
Low600-8002.5
Medium 900-11003.5
High1200-1600+6.5

Variable Speed Blower Motor

Variable Speed Blower Motors have Soft Start tech too. This increases motor lifespan and reduces start-up time. Plus, less energy use means cost savings in the long run.

Here’s a look at the characteristics of different blower motors.

Blower Motor TypeCharacteristics
Single-SpeedFixed speed, turns off & on as needed.
Multi-SpeedMultiple speed settings, manually selected. Can improve power use, but not always noise-reduction.
ECM (Electronically Commutated Motor)Variable speeds, precise control for optimal performance.

How Furnace Blower Motor Works?


To understand how a furnace blower motor works and how it can solve your problem, let me break down its main types. 

Airflow and Air Ducts

Furnace blower motor performance depends on airflow & air ducts. Proper functioning of these parts guarantees effective flow of temperature-controlled air throughout your home or office

The air ducts must be clean & free from blockages, also allowing for circulation. Additionally, airflow must be balanced to provide sufficient air to all rooms. Otherwise, the unit is almost useless.

To ensure good ventilation in each room, we can use dampers to adjust airflow. 

They adjust air leakage at specific points in the ducting pathway. To boost efficiency, flexible ductwork or sheet metal can be used.

Good design & structure aids in maintaining the same temperatures around the house, regardless of outside conditions. 

Insulating all system components will also deliver cost-effective warmness during cold winter months. It’s wise to have a professional install a tailored furnace blower motor system.

System and HVAC System

The Blower Motor is the device that powers airflow to circulate warm or cold air. Furnaces convert energy like fuel, electricity, or solar energy into heat with a heating element.

It works as a primary and auxiliary part in central heating, furnaces, or air conditioning systems. 

It moves warm or cold air through ductwork channels. To prevent damage, it needs regular maintenance.

Knowing about HVAC Systems helps you use resources wisely, while keeping your family safe. 

With more knowledge, you can also make your home more comfortable, while reducing monthly energy costs.

Air Handler and Air Conditioning System

Air handlers and air conditioning systems are essential for modern heating and cooling. Their purpose is to circulate air in buildings

Many understand that the air handler circulates air, but not that each part plays an important role. 

Air handlers and air conditioning systems are vital for maintaining comfortable environments. 

Let’s look closer at how they work. Their components include a furnace blower motor.

ComponentDescriptionFunction
Air FilterRemoves airborne particles and pollutantsImproves indoor air quality
Blower Assembly (with furnace blower motor)Blows conditioned air through ductworkDistributes hot/cold air in your home
Evaporator CoilAbsorbs heat from indoor airRegulates indoor temperature
Condenser Coil (in AC systems only)Releases heat outside the buildingKeeps temperature comfortable

Working with Thermostat

The furnace blower motor plays an essential role in heating systems by blowing air through the ductwork of your home. 

The thermostat controls it.

  • The thermostat sends a signal to the blower motor when the temperature drops.
  • The motor takes cold air from the return ducts and passes it over the heat exchanger.
  • The heat exchanger heats the air, and then the air is sent back into your home.
  • When the temperature rises above the desired level, the thermostat stops sending signals, and the motor shuts off.

Signs of a Problematic Furnace Blower Motor


To identify the signs of a problematic furnace blower motor, we will look into the below points:

Dust and Moisture

When it comes to furnace blower motors, dust and moisture can cause a problem. Dust can block air ducts and damage motor performance. 

Moisture can lead to corrosion, which can cause permanent damage. To avoid these issues, keep the furnace clean and dry.

Regular cleaning is key to preventing dust buildup. Not only does this affect airflow, but it also increases energy consumption. 

Change the filters frequently too, to capture particles before they settle in the air ducts or blower motor.

Moisture can come from leaks or poor ventilation systems, which allow humid air to pass through the air conditioner coil. 

Control humidity levels with a dehumidifier near the furnace. Seal cracks or gaps around openings that border pipes or vents, to stop moisture buildup.

Friction and Heat

Friction and heat are two major problems that can take a toll on the furnace blower motor’s performance. Friction happens when two surfaces rub against each other, causing wear and tear. This leads to strange noises and vibrations. 

Friction increases temperature of the motor parts, causing thermal issues. The higher heat damages the motor and can even make it useless. 

Recent studies by HVAC experts show that untreated blower motors with too much heat and friction have a lifespan 35% shorter than ones that run smoothly.

Age and Issues with Components

As furnaces age, components can show signs of wear. The blower motor is a critical part. Issues with it can lead to decreased energy efficiency, higher bills, and poor air quality.

Let’s look at how age affects the furnace blower motor.

Age RangeCommon Issues
0-5 yearsWiring faults Capacitorsbearings
6-10 yearsOverheating Relay issues
11-15 yearsDust buildupSlower performance
16+ yearsWorn partsInsufficient airflowFrequent cyclingTripping

Repairing or Replacing Furnace Blower Motor


To repair or replace your furnace blower motor, you need to understand how it works and what can go wrong. 

HVAC Contractor

Finding the right HVAC contractor can be tough, but it’s not impossible. A licensed professional is key to diagnosing and solving any issues that may arise, preserving your system for a long time.

Plus, preventive maintenance measures can save you a lot of money down the line. So, don’t wait contact an experienced HVAC contractor now and enjoy smooth operation throughout the year.

Call for Repairs or Replacement

If your furnace blower motor is not working properly, if you hear strange noises, weak airflow, or no heating, Call a certified technician.  They can diagnose and recommend the best solution.

Do-It-Yourself Tips for Furnace Repair

Furnace repair can be done without a professional. Here’s a five-step guide for repairing or replacing the blower motor:

  1. Turn off power. Flip the switch on the furnace and the circuit breaker that controls it.
  2. Removal. Take out the access panel and locate the motor. Remove screws, disconnect any wires.
  3. Testing. Use a multimeter device to test the motor. A reading higher than zero means there’s an issue.
  4. Repairing or Replacing. Clean the blower wheel and housing using soft-bristled brushes and a vacuum cleaner. Replacing part of an old motor can reduce its lifespan.
  5. Reassembly. Reassemble everything carefully and tightly. Clean all parts and reconnect the power supply. Then turn on power.

Maintaining and Increasing Furnace Blower Motor Life


To increase the life of your furnace blower motor, regular maintenance is key. In order to maintain and increase the life of your furnace blower motor.

There are a few solutions to consider:

Regular Service and Cleaning

The furnace blower motor is an important part of the heating system. Cleaning and servicing it regularly can increase its life, save money, and stop breakdowns. 

Here are some steps you can follow for cleaning and servicing:

  1. Take Out the Furnace Blower Motor: Carefully unscrew the bolts which hold the motor in place. Then, disconnect any electrical wiring connected to it.
  2. Clean the Motor: Use compressed air or a soft-bristled brush to remove dust, dirt, and debris from the motor blades, housing, and fins.
  3. Oil and Put Back Together: Spread lubricating oil on all moving parts of the blower motor assembly. Ensure to fasten all bolts securely.

Adjusting Speed and Energy Use

Follow these 4 steps to adjust speed and energy use.

  1. Find out your motor’s power rating and specs – it’ll tell you the max voltage it can take.
  2. Turn off the circuit breaker powering your furnace before tinkering.
  3. Spot the fan control switch on your blower motor.
  4. Change the fan control switch to reduce/increase airflow as desired.

Keeping Comfortable Temperature and Airflow in Room

To maximize the life of your furnace blower motor, proper care is essential. Cleaning, lubricating, and replacing faulty components are key.

  • Clean it regularly with a soft brush or vacuum.
  • Oil or grease the moving parts for smooth operation.
  • Replace worn-out parts like belts, bearings, or fans.
  • Professional maintenance annually is also recommended.

Conclusion


The furnace blower motor is what drives the airflow of the HVAC system. It’s responsible for circulating heated and cooled air in your home. Three main types of motors exist: single-speed, multi-speed, and variable-speed. The type of motor you have can impact how much energy it uses and how comfortable the temperature stays. 

About the author

Debarghya Roy: A heating systems author, Passionate about energy efficiency and sustainability, Sharing insights and empowering readers through informative blog articles.