What to Do If Your Furnace Won’t Turn On?

At Dugan Air, our technicians service all major furnace brands, and we often find a few common culprits behind a furnace not turning on. In this guide, we’ll go over the first steps to take and things to check when your furnace refuses to start up, explain common reasons for this issue, cover a few handy prevention tips, and offer next steps if your troubleshooting doesn’t seem to help. All warmed up? Let’s dive in.

Quick Safety Checks Before You Call for Repair If Your Furnace Won’t Turn On

If your heater isn’t working, there’s a chance a simple issue is to blame. Furthermore, some of these minor problems can be a hazard if left unchecked, so it’s always a good idea to run through these safety tips if your heater won’t turn on:

• Check thermostat: Confirm that your thermostat is on, set to ‘heat’ or ‘auto’, and is switched to the right temperature to make your furnace run.
• Inspect filter: A clogged air filter can cause a furnace to shut down, and filters should be changed regularly. Find yours and see if it’s visibly dirty, and replace it if needed.
• Confirm power supply: Check your electrical panel to confirm that the circuit for your furnace is switched on and working. Also, double-check that the power on the furnace is switched on.
• Inspect pilot light: For gas furnaces, check that your pilot light is ignited and burning a steady, bright blue. If it’s burning yellow or orange, flickering, or extinguished, you could be at risk of a dangerous gas leak, so call a professional right away.
• Open gas valve: If you have a gas furnace, make sure the gas valve is open.
• Check HVAC vents: Sometimes, severely clogged HVAC ducts can prevent heat from entering your home, even if the furnace is working well. Check HVAC vent grilles for major dust buildup, and call a pro for duct cleaning if you notice signs of a problem.

Common Reasons a Furnace Won’t Turn On

Furnace not kicking on? There are a few potential reasons for a heater not turning on, which range from quick fixes to more serious problems. These include:

Malfunctioning thermostat

Your thermostat is responsible for telling the heater when to switch on and off, so if there’s an issue with the thermostat’s sensor, power supply, or connection to the heater, it can prevent your furnace from running when it should. 

Gas supply problems

If your furnace is leaking gas, it not only means your gas heater won’t turn on, but it also places you at extreme risk of fire or hazardous gas inhalation. If you smell the rotten egg scent of gas, evacuate the home immediately and call for help from an emergency heating repair team.

Power troubles

Furnaces need a lot of electricity, and the load on your system can sometimes lead to circuit breakers tripping or fuses blowing. This might mean your furnace is consuming more power than your electrical system can handle, meaning you may need to replace your furnace or upgrade your electrical panel.

Dirty burners

If your burners get clogged up with dust and debris, they’ll struggle to ignite and burn less efficiently. For this reason, we recommend getting your burners thoroughly cleaned at least once a year, along with other key heater maintenance tasks.

Component damage

Furnaces are full of sophisticated parts that can get damaged through normal wear and tear. A cracked heat exchanger or an unlubricated blower motor can cause all kinds of heater headaches, including strange noises from the furnace, a repeatedly freezing heater, or even excess condensation leading to a heater leaking water.

Pilot light issues

If your gas furnace’s pilot light won’t stay lit or isn’t burning at the right intensity, your heater will struggle to function (or won’t run at all). Although you can safely relight an extinguished pilot light, repeated issues with the ignition system shouldn’t be ignored. Our HVAC pros often find that older furnaces in Franklin and Greenwood struggle with ignition due to dirty flame sensors — an easy fix that prevents costly breakdowns.

Dust buildup

Dust in your HVAC ducts and around the heater can cause all kinds of issues, stopping your heater from functioning efficiently or shutting it down entirely. Having your heater and ducts cleaned is an important part of a heating tune-up.

What to Do If Your Furnace Still Won’t Turn On?

As anyone who’s been through an Indiana winter can tell you, a functional heater is absolutely crucial in the colder months of the year. If you’ve run through the troubleshooting tips above and still can’t get your heater to work properly, it’s time to call for help from a local emergency heating repair pro. 

If you’re struggling with a furnace shutdown, call the HVAC repair pros at Dugan Air. We’ll inspect the entire system, diagnose the problem, and make any repairs needed to get the system running again. While we’re at it, we’ll also thoroughly clean, inspect, and tune up the entire system, ensuring each component is ready to run safely, effectively, and efficiently.

How to Prevent Furnace Problems Before Indiana Winter

The only better feeling than restoring a shut-down heater is avoiding the problem in the first place! While every heater will eventually break down, you can dramatically increase the lifespan of your system (and reduce the odds of a shutdown) with regular maintenance, cleaning, and tune-ups from a premium service provider like Dugan Air.

We suggest having your system professionally maintained once a year, ideally in the fall before you’ll be counting on your furnace daily. Not only will this help you avoid a sudden furnace failure, but you’ll also experience more consistent, reliable heating and higher energy efficiency. How’s that for a win-win-win?

Keep Your Heater Running All Winter Long with Dugan Air

Winter in Indiana can be a beautiful time, but it definitely starts to lose its charm when your heater is struggling to keep your space warm. At Dugan Air, we offer top-quality heating repair and maintenance services, helping homeowners with both shutdown units and the essential ongoing maintenance of these vital systems. For more info, prevention tips, or to schedule a gimmick-free furnace service appointment, don’t hesitate to contact us today. 

Frequently Asked Questions

Why won’t my furnace turn on even when the thermostat works?

If your thermostat is working, but the furnace isn’t, it could be due to power supply issues to the heater, an extinguished pilot light, clogged burner elements, or component failure. Contact a heating repair pro to inspect the system and get it working again.

How do I know if it’s an electrical or gas issue?

The top sign of an electrical issue is if your furnace won’t switch on whatsoever. Gas problems, on the other hand, generally present as issues with the pilot light or a system that seems to be running, but isn’t producing any heat. A professional can determine the exact cause of your problem.

What should I do if I hear clicking but no ignition?

If you hear clicking from your furnace, but the pilot light won’t ignite, immediately turn off the furnace and the gas and evacuate your home. This can indicate a gas leak, which is a serious hazard. Contact a repair pro right away to inspect and fix the system.

Dan Dugan

President
Dan Dugan is the President and co-owner of Dugan Air Heating & Cooling. A licensed HVAC professional with over 25 years of industry experience, Dan brings extensive technical expertise and leadership to the company he and Sue founded in 2009. He remains deeply involved in training, innovation, and maintaining the company’s reputation for integrity-driven service across Central Indiana.