If you’ve run into problems with your furnace blower motor in the past, you’re not alone. Blower problems are some of the most common in furnaces as among the hardest working furnace components. In fact, rarely can anyone go the entire heating season without blower motor mishaps.
Fortunately, you can personally locate and troubleshoot the blower motor. You can even replace the blower motor if it’s damaged beyond repair.
Read on to learn more about the furnace blower, what it does, how to find it, and how to reset your fan.
What is the Furnace Blower Motor, and What Does it Do?
The furnace blower motor is a fan within the furnace that helps push out conditioned (warm) air out of the furnace. Its primary role is to create air motion that directs warm air outside the furnace and into your home.
However, it also has two supplementary (indirect) functions;
- Disperse warm air throughout the home: It doesn’t do this directly. Instead, it generates and sustains the air circulation necessary to disperse warm air throughout the home for even heating. Even heating is important to prevent cold spots.
- Draw cold air into the furnace: This also happens indirectly, again thanks to the air circulation created by the rotation of the blower blades. The circulation creates artificial convection that forces cold air to enter the furnace for heating.
Where is the Furnace Blower Motor Located?
The blower motor is located in a box at the base of the furnace next to the air filter. The location is strategic in that the fan rotation helps pull return air through the vents and forces the air through the filter. Remember that furnace air filters trap up 99% of air impurities, including dust, pollen, and debris.
These elements can make return air even denser, meaning it will likely linger outside the return vents if everything is left to nature. The rotating blades in the blower motor create a vacuum and pulling effect that helps force return air through the filter. When you switch ON the furnace, it blows the cold air across the burner in the combustion chamber.
Then the heat is transferred to the heat exchanger and forced out into the home’s ductwork thanks to the constant blowing motion.
How to Locate the Furnace Blower Motor
If you’d like to access the furnace blower motor, perhaps to inspect it or troubleshoot the wiring or motor, proceed as follows;
- Shut down the furnace: Turn off the furnace at the circuit breaker. Then switch off the power button on the furnace. Also, remember never to touch the furnace with wet hands.
- Remove the access/front panel: How to remove the panel varies depending on the type of furnace. Whereas you can easily lift/pull the panel off in some models, you need to remove a few screws to remove the panel in others.
- Remove the bottom panel: As we mentioned, the furnace blower motor is located in the bottom compartment. So, you need to remove a second panel to access it.
- Find the blower system: The blower motor resembles a hamster wheel and is fixed to a rail within the compartment.
How to Tell if Your Furnace Blower Motor is Bad
It’s often easy to tell if the blower wheel is bad, though sometimes you may need further tests to prove that it’s unsalvageable. Always begin by watching out for the following symptoms;
An unusually quiet furnace
Furnaces are not silent appliances. Even a brand-new furnace produces a characteristic soft humming sound that’s very audible, especially when standing within a few feet of the furnace. This sound originates from the rotating blower wheel and is often a sign that the furnace is running.
So, if everything goes dead silent suddenly, the furnace is off, or the blower wheel is not running.
Strange furnace sounds
At the other extreme, strange noises can also be a sign of a damaged or broken furnace blower wheel. First, the blower system has wheels that turn to move air. If these wheels are broken or bent, you may hear loud screeching sounds.
Additionally, the blower motor uses bearings for smooth, low-noise rotation. So, if the bearings are broken or worn, the blower may produce a screeching or grinding sound.
The blower runs but doesn’t blow warm air
Sometimes you may hear the blower humming as usual but not get any warm air from the supply vents. Whenever this happens, the blower fan is the likely culprit. Often, it happens when the blower capacitor is blown.
The blower motor depends on a special capacitor to start. If the capacitor is defective or aging, it may not hold enough power to start the blower motor. So, the motor will hum because it’s getting power. But it won’t run, meaning you cannot get warm air.
A burning smell from the base compartment
You may need to open the top compartment to verify that the smell is coming from the bottom compartment. Is, so, it may point to overheating and possible damage within the blower motor. Blower motors overheat when the lubrication wears out.
They may also overheat if the fan has run too fast for too long. Or it could be the result of old age.
Furnace error codes
Many modern furnaces have control panel displays with error-reporting capabilities. For instance, an LED light may flash a specified number of times to signal a specific issue. Or it may display an error code such as 414.
You can quickly check your owner’s manual to check whether the flashing LED or error code signals a blower motor problem.
What Can Cause a Furnace Blower Motor to Stop Working?
A furnace blower motor can stop working for various reasons. However, the following are the eight most common reasons;
The thermostat is the brain of the furnace. It tells your furnace when to start and when to stop. It also determines when the furnace blows fast and when it blows slowly. Thus, the furnace or a component within it can refuse to run if your furnace is broken or wrongly set.
Typically, the blower motor will stay OFF if the thermostat setting is below room temperature. It can be off due to malfunction or the wrong setting.
The fan is not getting power
The furnace gets its power from two primary sources. The starting power comes from a special capacitor, while the running power comes from a stepdown transformer within the furnace’s control board. If any of these power sources are compromised, the blower will stay OFF.
The drain pan is full
Over 90% of furnaces in use today are condenser fans that extract moisture from hot air for efficiency purposes. The moisture then condenses into a drain pan, which drains automatically, typically through gravity. However, if the drainage process is compromised, the water can back up into the furnace.
Since this can cause internal damage, modern furnaces have a drain pan lockout switch to shut down the heating process whenever the pan is full. The switch also discontinues the blower motor.
The blower motor is defective or damaged
Finally, you should also consider that perhaps the blower motor is defective or even dead. For example, perhaps one of the blades is broken. If a blade is broken, the fan will make noise and cannot push air as strongly as before.
Alternatively, the belt-drive could be worn or the furnace capacity (discussed earlier) aged. Or the motor could be dead.
How to Reset a Furnace Blower Motor
If the blower motor simply shut down due to overheating or a lockout switch, a simple reset could restore it to normal function. The best part is that resetting a furnace blower motor is a straightforward process that doesn’t require professional intervention. It also takes five minutes at most.
- Shut down the furnace: You need to turn off three parts of the furnace system. First, shut it off at the breaker. Then, head to the furnace and turn off the onboard switch. Finally, turn off the gas supply at the valve.
- Allow the furnace to cool down: If the furnace had been running for at least 15 minutes before the issues began, allow it at least two full minutes to cool down. Working on a hot furnace exposes you to serious burn risks.
- Access the blower compartment: We discussed the process earlier. Essentially, you need to remove the front panel and then the bottom compartment panel. You’ll see the hamster wheel-like blower motor.
- Locate the restart button: Check the top of the blower motor for a switch atop a raised surface. It’s usually a red or yellow switch.
- Press the button for up to 30 seconds: The actual time varies from one furnace to another. Feel free to check your owner’s manual for manufacturer guidance. However, generally, you need to press it for at least five seconds. Then release it.
- Replace everything and start the furnace: Put back the relevant panels. Then restore the gas supply by turning on the valve. After that, switch back power at the breaker. Finally, switch on the furnace to see if resetting the furnace blower motor solved the original problem. If not, consider professional repair or replacement.
Knowing how to find and reset the furnace blower motor can save you a lot of money whenever you run into blower fan issues. However, don’t hesitate to call for professional troubleshooting and repairs if the problem persists.