Why Is My Furnace Not Working?
Written By: Alexis Bennett
Edited by: Andrew Dunn
Are you concerned about your furnace not working correctly with cold winter weather right around the corner? If so, we may be able to help.
In this guide, you will find the answers to frequently asked questions, like:
- What are the most common reasons my furnace won’t turn on?
- Why isn’t my heater blowing warm air?
- What is the best way to handle heating repair service calls?
- What can you do to prevent significant heating system malfunctions?
Below you will find the most common HVAC problems, ways to troubleshoot your furnace, and when you need an HVAC professional. Heating season has already begun in some parts of the country.
So, let’s begin.
What's In This Guide?
What Are The Most Common Reasons For Your Furnace Not Working?
Your heating system contains many parts that all have to work correctly to heat your home. If any of those parts breaks or stops working the way it should, it can throw the entire system off.
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Something as small as the batteries dying in your thermostat can have significant implications on your heater and the health of vulnerable groups, like elderly parents, grandparents, and babies under a year old.
Knowing what could potentially be causing your heater not to work, you are one step closer to fixing it. So, here are the most common reasons your furnace might not be working:
The HVAC Thermostat Is Not Working
Your thermostat is like the brain of your HVAC system. When the temperature in your home drops below the setting on your thermostat, your heater turns on. When your home’s temperature reaches the correct temperature, the furnace stops.
However, if it is not working properly, it will not send the correct signal to your furnace or air conditioner. So, the first thing you should do when your furnace is not working is check your thermostat settings.
Make sure that it is set to heat. Then, turn the temperature up, so it is higher than the room temperature. If your HVAC is functioning, you should hear it turn on.
If you have a battery-operated thermostat, your heater may not work properly if the batteries are low. Thermostats with a removable front panel can also get dust in them, which may cause them not to work properly.
There are pegs on the back of your thermostat face. If the prongs get damaged, it will also cause your HVAC system to malfunction.
So, make sure that all of the prongs are there and that none of them are bent or damaged. If they are, you may need to replace your thermostat.
You can fix the thermostat yourself if you have experience with wiring. Otherwise, you need to contact an HVAC repair company.
Your Air Filters Are Dirty
Clogged or dirty air filters can take a toll on your heating system. So, the first thing you should do is check your furnace filters.
Many homeowners overlook them, especially during the winter season. That is not a good idea, though. Just because you are not using your HVAC does not mean you should not change dirty filters.
Your entire central air conditioning system, including your furnace, uses the same filters to clean the conditioned air before releasing it back into your home. So, it would be best if you replaced them every 30 to 60 days.
If you have not been changing your filters regularly, there is likely a lot of dust and lint built-up in your air handler and ductwork. Clogged filters are not as efficient at trapping particles before they reach your air handler.
They can also restrict the flow of air into your heating system. Which makes your system less energy-efficient and puts a strain on your furnace.
Your Pilot Light Went Out
If the pilot light goes out, the gas can continue to escape from the line. If that happens it will build up in your home until the gas is shut off because you are not burning it.
Natural gas is hazardous and highly flammable. It is an odorless and colorless gas, but chemical refineries add a distinctive smell to alert homeowners of gas leaks.
If you smell natural gas in your home, you should leave immediately and call the utility company to let them know.
They will send a technician to investigate and, if necessary, locate the source of the gas leak. Otherwise, if your pilot light went out and you do not have natural gas in your home, you can re-light it, and your heater should start working again.
How To Re-Light Your Pilot Light
If you recently purchased a new home, or if you have not used your heater yet, the pilot light may need to be re-lit. The first thing you need to do is make sure the gas is on.
Then, you will want to locate the gas bypass button. You need to hold that and the electronic ignition switch at the same time for the pilot light to ignite.
For more information on relighting the pilot light, check your owner’s manual, or watch this video:
Your Thermocouple Is Malfunctioning
The thermocouple is a sensor that works in conjunction with your electronic ignitor. When it is working properly, it keeps the pilot light lit.
When the sensor stops working, your pilot light will go out. So, if you notice that your pilot light is going out more often, it is likely your thermocouple.
The Circuit Breaker Is Tripped
All new homes and HVAC systems contain circuit breakers that allow you to turn the power off to one or both major heating system components to perform routine maintenance.
You can usually find these small square circuit breaker box with a power switch located near your indoor or outdoor HVAC unit. Or, you may need to check the main electrical panel breaker box to be sure that a circuit breaker there is not tripped.
You Need To Replace Your Blower Motor
The blower motor is an essential component of your heating system. It is responsible for blowing the heated air through the air ducts and out of TNT vents into your home.
If your blower motor is not running properly, your heater will struggle to increase the temperature in your home. If you do not feel any forced air coming out of your vents, a broken blower motor may be responsible.
There Is A Gas Line Leak
If you have a natural gas furnace, your unit will not run without a constant gas supply. If there is a leak in the gas line, your unit will not heat your home.
If you smell gas, you should leave and call your gas company. They can send someone out to shut off the gas at the gas valve. Then, you will need to call an HVAC repair technician to repair the AC line.
Your Furnace Coils Are Dirty
Dirty coils in your furnace can wreak havoc on your HVAC system. If coils become too clogged, your furnace temperature can get too hot causing the system to shut off.
The Heat Exchanger Is Malfunctioning
The heat exchanger is responsible for moving heated liquid through your HVAC system. If it is not working, your heater will not work.
Unless your HVAC is older, it is unlikely that the heat exchanger is causing the issue. These components are manufactured to last between 10 and 20 years. However, there are some factors that can make them go bad quicker.
For example, if you run your furnace frequently with a clogged air filter, the restricted hot air can cause your furnace to overheat. Eventually, the high temperature may cause stress fractures.
The same thing can happen if the blower motor is broken. That is one of the reasons you should never put off furnace repairs. The longer you wait, the more damage your system could sustain.
What Should You Do If You Can’t Fix The Furnace?
Some of the most common problems with your furnace require the assistance of a trained professional, while others are relatively simple to fix yourself.
However, if you do not know what you are doing, attempting a DIY furnace fix can be dangerous and costly. Hiring a licensed HVAC professional to handle furnace maintenance, will give you peace of mind.
Here are some steps to help you find a qualified technician:
- Perform a search for the top service contractors in your area.
- Call several companies for quotes and to establish availability.
- Check online reviews for your first and second picks.
- Make sure that the contractor you choose has the correct licenses.
- Set up an appointment for a system diagnosis.
Final Advice If Your Furnace Is Not Working
If you live in a cold climate, you need a working furnace during the heating season. Aside from changing your air filters routinely and keeping your HVAC coils clean, a home warranty is one of the best ways to ensure that your system is operating properly.
As a home warranty customer, you do not have to worry about furnace troubleshooting and attempting a DIY fix that might make things worse. Home protection companies have extensive networks of qualified furnace repair professionals.
The leading home warranty providers vet their contractors and guarantee labor and parts.
It does not matter if you have a blown fuse, broken thermocouple, or a malfunctioning blower motor. Home warranties cover furnace repairs and replacements up to the limits of your plan.
While your plan will not cover repairs for the first 30 days, some companies offer discounts for service during the waiting period. Other providers offer value-added services like free semi-annual HVAC maintenance and air filters, so you can keep your high-efficiency furnace operating optimally.