Furnace Fan Not Working: Troubleshooting and Fixes

A furnace fan plays a crucial role in distributing heated air evenly throughout your home. If the furnace fan not working correctly it can drastically reduce your furnace’s efficiency and leave your home colder than it should be. Here are some tips to troubleshoot and address the issue if your furnace fan isn’t working.

Key Checks for a Non-Working Furnace Fan

The table below summarizes key checks you should perform when your furnace fan isn’t working:

Check Category	Steps & Tips
Power Source	Make sure the furnace’s on/off switch is in the “on” position. Check if the circuit breaker has tripped.
Thermostat	Ensure the thermostat is set appropriately. If set too low, the furnace may not start. Try switching the thermostat setting to “on.”
Blower Motor	If the blower motor is humming but not starting, the problem might be a bad capacitor. Ensure the power cord hasn’t melted and no fuse has been blown. Unplugging the fan for a few minutes and then plugging it back can sometimes reset the motor.
Furnace Flame and Heat Exchanger	Check the furnace flame for a completely blue color. Yellow, red, or orange flames indicate dust and dirt buildup. Inspect the heat exchanger for cracks.
Furnace Error Code	The furnace’s control board should have a small indicator light on it. The light will flash in a sequence depending on the furnace’s status. Check your owner’s manual for the blink codes for your furnace.

Checking if the Furnace Blower Motor is Receiving Power

If your furnace blower motor doesn’t seem to be getting power, the following steps can help you troubleshoot:

Steps to Check Power	Details
Turn Off Power	Turn off the power to the furnace for safety reasons. Do this either from the power furnace switch or from your breaker inside the Consumer Control Unit.
Remove Access Panels	Open the casing covering the furnace blower motor to expose the internal structure.
Test Continuity	Use a multimeter to check the continuity of the motor circuit. An infinite resistance reading indicates an open circuit and a defective motor.
Test Thermostat	Ensure the thermostat is set correctly. Try switching the thermostat setting to “on.”
Check Error Codes	Check your furnace’s control board for a flashing indicator light. The specific light blink codes can help diagnose issues.

Troubleshooting a Malfunctioning Furnace Fan

Before calling for professional help, there are several steps you can take to identify and potentially resolve the issue.

Issue	Troubleshooting Steps
Power source	Make sure the furnace’s on/off switch is in the “on” position and check to see if the circuit breaker has tripped.
Thermostat setting	Make sure the thermostat is set appropriately. If set too low, you may be cold but your furnace thinks everyone is cozy at 50 degrees. Try switching the thermostat setting to “on.” This adjustment will lock the fan into an always-on state.
Blower motor	If the blower motor is humming and lights turn on, but nothing is happening, your furnace issues probably stem from a bad capacitor. Inspect the wires in your furnace to make sure that the power cord hasn’t melted or a fuse hasn’t been blown. Try unplugging the fan for a few minutes and then plugging it back in again. If the fan in a furnace is not working, this is an indicator of a worn down or cracked belt that needs to be replaced.
Furnace flame and heat exchanger	If you have cool air but a steady airflow, your blower motor is working but your heat exchanger or burner is not. Check the furnace flame for a completely blue color. Any yellow, red, or orange indicates dust and dirt buildup on the burner. Inspect the heat exchanger for cracks, which can cause a safety hazard.
Furnace’s error code	The furnace’s control board should have a small indicator light on it. The indicator light will flash in a sequence, depending on the furnace’s status. For example, if there is an issue with the furnace, then the light will flash in a specific sequence to tell you what is keeping the furnace from running.

Steps to Check if the Furnace Blower Motor is Receiving Power

If the furnace blower motor is not working, it might be due to a lack of power supply. Here are the steps to verify if the blower motor is receiving power:

Steps	Description
Power off	Turn off the power to the furnace for safety measures.
Remove panels	Take off the furnace access panels to expose the blower motor.
Test motor circuit	Use a multimeter to check the continuity of the motor circuit.
Test thermostat	Ensure that the thermostat is set appropriately.
Check error code	Look at your furnace’s control board for the error code.

Common Causes of a Furnace Blower Motor Not Receiving Power

Various issues can prevent the furnace blower motor from receiving power:

Issue	Description
Power source problems	Ensure that the furnace’s on/off switch is in the “on” position and the circuit breaker hasn’t tripped.
Capacitor issues	A humming blower motor that doesn’t start could indicate a faulty capacitor. Check the wires to ensure the power cord hasn’t melted or a fuse hasn’t been blown.
Thermostat issues	An incorrectly set thermostat could prevent the blower motor from receiving power.
Blower motor problems	A worn-out or broken blower motor can stop the furnace from operating correctly.

Understanding the Furnace Blower Motor Capacitor

The furnace blower motor capacitor regulates power input to the motors in your furnace. Acting like a battery, it holds a charge to start the blower motor and keeps the motor running by allowing all electricity to pass through it. Capacitors are crucial components that ensure your home remains comfortable year-round.

The resistance for a functioning furnace blower motor capacitor typically ranges between 1 and 20 ohms. A reading within this range suggests that the capacitor is functioning correctly. However, an infinite reading indicates an open circuit and a defective capacitor, while a lower-than-normal reading may suggest a problem with the capacitor.

A faulty furnace blower motor capacitor may exhibit various symptoms. These include the blower motor not starting, the motor running slower or weaker than usual, a humming sound from the furnace without the motor starting, the motor running hotter than usual, and frequent on-and-off cycles of the blower motor.

Generally, a furnace blower motor capacitor should be checked by a professional HVAC technician every few years to ensure it functions correctly. Factors such as the capacitor’s age, environmental conditions, frequency of use, and signs of wear or damage can influence its lifespan, which typically ranges between 10 to 20 years. However, if signs of wear or damage are evident, immediate replacement is necessary to prevent further furnace damage.

Replacing a Faulty Furnace Blower Motor Capacitor

If the furnace blower motor capacitor is indeed faulty, you might need to replace it. While this is something you can often do on your own with the right tools and safety measures, it might be best to hire a professional HVAC technician if you’re not comfortable with it. Here’s a general guide on how to replace a faulty furnace blower motor capacitor:

Steps	Description
Safety first	Always turn off the power to your furnace before doing any work.
Identify the capacitor	The capacitor is usually located near the furnace motor. It is a cylindrical object that may be either standing up or lying down, and is generally metallic in color.
Remove the old capacitor	Carefully disconnect the wires from the old capacitor. Be sure to take note or a photo of how the wires are connected so you can replicate it when installing the new one. Then, remove the old capacitor from the furnace.
Install the new capacitor	Secure the new capacitor in place, then reconnect the wires in the same configuration as they were on the old capacitor.
Test the furnace	Turn the power back on and test the furnace. The blower motor should now start up as usual.

Preventive Maintenance for Furnace Blower Motor

Preventing furnace blower motor issues can often be achieved with regular preventive maintenance. Here are some recommendations:

Steps	Description
Regular cleaning	Dust and debris can hamper the blower motor’s performance. Regular cleaning can prevent these issues and extend the lifespan of the motor and capacitor.
Scheduled maintenance	Annual or semi-annual professional maintenance can ensure the blower motor is functioning correctly, and any potential issues can be addressed before they become severe.
Replacement	Even with preventive maintenance, parts will eventually wear out. Replace the blower motor or capacitor when they show signs of aging to prevent sudden failure.

Conclusion

A faulty furnace fan can disrupt the comfort of your home, but understanding how it works and how to troubleshoot can help maintain optimal functionality. The furnace blower motor and its capacitor play an integral role in this process, and regular maintenance can help prolong their lifespan. However, when issues do arise, it’s crucial to address them promptly to prevent further complications.