Furnace Not Working?
Few things are more frustrating than turning up the thermostat on a cold day only to realize your furnace isn’t working. Before you panic, know that many furnace issues have simple fixes you can try yourself. Others require the help of a professional. This guide walks you through the most common causes, safe troubleshooting steps, and what to do if your furnace still refuses to cooperate.
Common Reasons a Furnace Stops Working
Not every furnace failure means you’re in for a big repair bill. In fact, a large percentage of “no heat” calls end up being something simple. Here are the most common culprits:
- Thermostat issues – Dead batteries, incorrect settings, or a thermostat that’s not set to “Heat.”
- Power supply problems – A tripped breaker, blown fuse, or switch near the furnace accidentally flipped off.
- Clogged air filter – Restricted airflow can cause the furnace to overheat and shut down.
- Gas supply issues – Closed gas valves or interrupted service prevent ignition.
- Ignition or pilot light problems – A dirty flame sensor, faulty igniter, or extinguished pilot light.
- Airflow blockages – Closed registers, blocked vents, or leaking ductwork.
Here’s What to Do
Check your filter
We always recommend checking your furnace filter before calling for any HVAC service. A dirty filter can cause your system to work harder than it needs to and eventually shut down all together. If your filter is dirty, you may find that air is still blowing from your vents, but it may not be very warm or it may be less air overall. To check if the filter is dirty, just pull it out from the furnace and try to see through it. If you cannot see through the filter, then it needs to be changed. If the furnace isn’t working properly and you find a dirty filter – go ahead and replace the filter and wait an hour or so to see if operation improves.
READ MORE: How often to change furnace filter
Check your thermostat
It sounds like a no-brainer, but if your furnace is not working you should go verify that you have your thermostat set to “heat mode.” It’s possible one of the kids played with it or you have a scheduled setting that is causing the temperature to be lower than you’d like. If there is a thermostat settings issue then it’s likely that the furnace is still able to blow air, but it may not blow when you want, or it may not be keeping up the temperature that you’d like.
If the thermostat screen is completely blank or has a low battery indicator on the display and the furnace is not blowing any air, try changing the batteries. If you look inside the battery compartment and see corrosion, it is likely that the batteries are the issue.
Make sure the furnace switch is ‘on”
The furnace switch turns power on and off to the furnace. It is on the side of the furnace or mounted on the wall. If this is switched off then your furnace will not be able to operate at all and the furnace will not turn on. You may also notice that there is no power to your thermostat and it has a blank screen. Turn the power switch back to the “on” position and see if proper operation commences.
Check air vents
Check the vents in each room to make sure they are open and that airflow is not being obstructed by furniture or other items. If it is an issue with the vents in the home, then your furnace will still be blowing warm air, but it may be less air than desired in certain rooms, causing those areas to be cold.
Check for tripped breaker
If the furnace is unable to blow air at all, check the breaker box for a tripped breaker that is in the “off” position. Hopefully your breaker box is labeled neatly so it is easy to find the breaker that is responsible for power to the furnace. If you find the breaker for the furnace is off, flip the switch back on to see if that solves the problem.
Older furnace? If you have an older furnace – think 20 years old or more – you may also want to check to see if the pilot light is lit. You can do this by looking through the window on the furnace. You should see a blue flame. Pilot lights are no longer used on newer, more efficient furnaces.
Read More: How to Light a Furnace
These are the main areas you can check yourself if your furnace isn’t working. There are many other culprits inside and around the furnace that could be causing your issue like the flame sensor, blower motor, limit switch and much more. We do not recommend an attempt at DIY repair or diagnosis on any of these furnace components. If the above doesn’t seem to fix your issue, you should call for professional furnace repair.
Furnace Maintenance
Getting regular maintenance on your furnace will help to ensure less breakdowns and a longer lifespan. Your furnace is a big investment so protecting it and making sure it works as efficiently as possible is important. Heating maintenance is recommended annually. Your tune up does not have to be completed in the fall, any time during the heating season is sufficient to perform maintenance.
When to Call a Professional
While basic checks are safe for homeowners, there are certain situations where you should stop troubleshooting and call a licensed HVAC technician:
- Persistent short-cycling or repeated shutdowns.
- Yellow, flickering, or uneven burner flames (instead of steady blue).
- Strong smells of gas, burning, or electrical overheating.
- Cracked heat exchanger or visible rust/soot around the furnace.
- Repeated breaker trips or electrical failures.
- Furnace older than 15–20 years with frequent issues.
Trying to repair these problems yourself can be unsafe and may make things worse. A trained technician can diagnose the root cause, perform a safe repair, or advise if replacement is the better long-term option.
Contact A Furnace Repair Company
If your furnace is not working and you are in need of furnace repair or furnace maintenance near Cincinnati, OH – contact Quality Comfort Home Services by calling 513-620-4822 or booking service online. We also offer emergency service if your furnace decided to stop working on the weekend (don’t they love to do that!)