What Can Cause a Furnace to Stop Working?

April 26, 2023


A furnace that stops working can be caused by any of the following:

  • An electric switch/breaker or gas line that has been turned off
  • A dusty, dead, or broken thermostat
  • A dirty furnace filter
  • A clogged chimney exhaust flue
  • Restricted drain lines
  • Blocked or leaky ducts, or blocked vents
  • A blocked intake or exhaust
  • A dirty flame sensor or dirty burner flames
  • An un-lubricated furnace blower motor
  • Worn out ball bearings
  • A slipped or frayed blower belt
  • A faulty ignition system

As you can see, when a furnace has stopped working, a long list of things could be the cause. Fortunately, some of the above items can be easily and inexpensively solved without needing to call a professional.

Of course, if the list seems too overwhelming for you to take on yourself, Yes! has perfected furnace maintenance and repair so you don’t have to give DIY repair a second thought. 

Simple & Easy Fixes – Things to Check Before You Call a Repair Service

If your heater is not blowing hot air or your furnace goes out, there are many things that could be the cause. Here is further information on what to do next. 

How Do You Reset a Furnace?

When your furnace stopped working, it may only need to have a reset done. To reset a furnace, it depends on whether you have an electric furnace or a gas furnace:

To reset if your electric furnace stopped working:

  • Find the reset button. It’s usually painted red or yellow and located on the bottom and back of the blower motor.
  • Push the button back in if it has popped out.
  • Hold the button down for 30 seconds.

To reset if your gas heater stopped working:

Note: Most homeowners assume that if they have a gas heater, then they have a pilot light. While this is true of very old furnaces (30+ years old), furnaces now use a hot surface ignitor instead.

  • Check to see if the hot surface igniter is glowing brightly by looking through the front cover when the heat should be on.
  • Turn the thermostat all the way down.
  • Turn off the furnace’s power switch.
  • Turn off the furnace’s main gas supply.
  • Leave on the pilot gas supply.
  • Relight the pilot flame by holding a lit match up to the pilot flame’s jet opening (this is located inside the furnace).
  • Turn back on the power to the furnace.
  • Turn back on the main gas supply.
  • Press the reset button for 30 seconds.
  • Turn up your thermostat, which should ignite your furnace.

What Would Cause a Furnace Not to Kick On?

A furnace might not kick on if it is experiencing any of the following problems:

  • The front panel that covers the blower motor isn’t securely fastened.
  • Your thermostat is full of dust, its batteries are dead, or the wiring is broken.
  • There isn’t any power to the furnace due to a flipped switch, blown circuit breaker, or broken or corroded wires.
  • The air filter hasn’t been changed and it’s dirty and clogged.
  • A burned-out hot surface igniter.
  • There is an insufficient supply of gas because the gas valve isn’t fully turned on.
  • There are blower motor issues which are indicated by a red or off light (rather than green and blinking) in the furnace’s inspection window.
  • There is excess water in the condensation pan, which means there are probably blockages preventing water from draining or your furnace’s condensate removal pump is broken.

Tools Required for DIY Fixes

Here is a list of tools that may be needed for DIY fixes if your furnace stopped working:

  • Screwdriver
  • New batteries for your thermostat
  • A vacuum for cleaning excessive dust from the furnace
  • Mastic sealer or professional quality metal foil duct tape for sealing HVAC ducts
  • Bleach for mixing with water to clean and flush the drain lines
  • Ten-weight non-detergent motor oil to lubricate the blower motor
  • A new belt for the furnace blower
  • ½” mesh hardware cloth for replacing window screen mesh that may be covering the intake or exhaust outside of the house
  • A water hose for rinsing dirt and debris out of the housing of the outdoor compressor unit
  • A match for reigniting the pilot light

Now, a word about furnace filters. Not changing them (or installing the wrong type) can cause a furnace to stop working. Plus, choosing the right one can make a big impact on the efficacy and efficiency of your furnace. Our knowledgeable and experienced pros at YTes! can give expert recommendations that work perfectly with your specific furnace.

Filter options include:

  • Disposable fiberglass are the basic filters. They prevent larger particles from clogging up your system, but do little to clean the air you breathe.

  • Disposable pleated filters are made from polyester or environmentally-friendly cotton paper. They block large particles and some small ones such as spores and mites. The downside is that they are more resistant to air flow so your system may be more expensive to run. However, they are recommended because they are much better at protecting your furnace and air conditioner.

  • Thicker pleated filters contain more surface area for catching pollutants and contaminants. Some of these filters even have smaller pores that capture more particles while still allowing full airflow. The filter’s added thickness offers more efficiency and lasts longer. 

  • Disposable electrostatic filters contain cotton or paper fibers that are self-charging and trap small particles. These can be a good way to go for homes with pets, children, or people who smoke.

  • Permanent electrostatic filters are similar to disposable versions, but the filter fabric can be removed and machine washed. They cost a bit more but can be reused for 6-8 years before needing replacement.

  • Health HEPA Quality MERV 13 filter is considered top of the line for its highest pleat count and ability to trap respiratory irritants such as smog, bacteria, and viruses.

Still Need Help? Call the Professionals at Yes!

If you’ve tried the above DIY suggestions and still your furnace isn’t working, it’s time to call for professional furnace repair. For additional information on HVAC services, call our team at 844-216-9300 and speak with a technician today.

Last Updated: February 22, 2024