It is never fun when the furnace fails in the middle of winter. Not only is this extremely uncomfortable (especially in areas that experience very low temperatures) but also inconvenient. There are also safety issues to consider, especially when the weather is freezing. This is not the ideal time for you to be looking for an alternative source of heat, especially when you are feeling cold. If your furnace seems to be giving up on you, don’t despair. There are things you can do right now as temporary measures to keep your home heated.

Why Is My Furnace Not Turning On?

Homeowners rely on furnaces to create and maintain a comfortable indoor environment. As temperatures dip, you would expect the furnace to turn on and generate heat. Unfortunately, it may fail at this very basic function. Now, this does not always point to a serious issue. In some cases, the solution is fairly simple and can be done with just a few tweaks. Here are steps you should consider:

Check The Furnace Circuit Breaker & The Furnace’s Power Switch Position

furnace circuit breaker

If the furnace is not producing heat, the first thing you need to check is its power supply. It is likely that the power was not turned on or the power supply was cut off at the breaker. This is true even with models that run on propane or gas. Some of the furnace’s components still require electricity to run. Check the position of the power switch and confirm if it is in the ‘On’ position. Check the circuit breaker panel as well and make sure it is on.

Look At The Condition Of The HVAC Filter

The air filter is an important component of your HVAC system. Air filters trap particulates that pollute the air that is being circulated inside the house. If the HVAC filter is dirty or damaged, it may not be trapping particulates as it should and could be causing improper airflow.

Inspect the Gas Valve Or Oil Tank (Depending On Your Fuel Source)

oil tank gauge

In some cases, your furnace may fail to produce heat because it does not have fuel for proper ignition. It is likely that the oil tank is near-empty, which means that you only need to call for an oil delivery to fix the issue. You can avoid this inconvenience if you check the level of fuel periodically and call in advance for a top-off, especially during the winter when there is a higher demand.

If you have a gas-powered furnace, check the gas valve. It is usually located about 5 to 6 feet from the furnace. It has a small lever or handle that can be turned. The lever is usually brightly colored. If the lever was closed for some reason, it is likely the reason why the furnace is not turning on. Turn the gas valve lever to the ‘On’ position to allow gas to flow through the pipe.

Note: A gas valve that is in the ‘Off’ position sits perpendicular to the gas pipe. If it is parallel with the gas pipe, then it is open.

Check the HVAC Air Vents Around Your Home

image of an hvac air vent

The furnace system relies on a good input and output of air. This means that for the system to work properly, it has to be able to pull in air and distribute it without obstacles or blockages. In some homes where certain rooms or spaces are unoccupied for long periods of time, some homeowners close the air vents to redistribute the air to other areas in the house. This is a cost-saving measure that many homeowners use. However, if there are too many air vents that are closed, this will affect the performance of the furnace. As a response to the overwork, it will shut off.

Inspect the Condensation Pan and Drainpipe

As your furnace runs, it will produce condensation. This is a normal part of its operation. To catch any water or moisture that it produces, the furnace is designed with a drainpipe and a condensation pan. Over time, debris could accumulate inside the drainpipe, preventing the proper drainage of water out of the system. If water has built up within the unit towards the condensation pan, the furnace will automatically turn off.

Furnace’s Flame

gas furnace flames

The flame is ignited when the furnace system is turned on. You can view this flame within the ignition area through a small window in the furnace. A good flame to have is one that is a bright blue color. If the flame is off, then no ignition occurred, which is why the furnace is not producing any heat. If the color is orange, yellow, or any other shade other than blue, you should get in touch with your local HVAC technician right away. There is likely a serious issue that needs to be fixed as soon as possible.

A Dirty Air Filter

Air filters collect dirt, dust, pollen, spores, and dander from the air so that the furnace only releases clean, warm air. Filters, however, do become dirty and clogged, making it more difficult for the furnace to distribute air. When airflow is a problem, the furnace becomes inefficient. Once the air filter has become severely clogged, the buildup will suffocate the furnace. As a safety precaution, it will likely shut off. Replacing the air filter should fix this problem.

A Safety Precaution: Before inspecting the furnace system, turn off the power to the unit. Locate the circuit breaker for the furnace and turn it off. Never work with the HVAC system if it is still being supplied with electricity from an outlet. Replacing the filter, opening vents, and other simple tasks are manageable by homeowners. Other tasks should be left to a professional HVAC contractor.

When To Call For Furnace Repairs

Once you have tried all the steps recommended above and your furnace still does not turn on, it is time to call a professional HVAC technician. A trained and licensed technician can perform a thorough inspection of the unit, do troubleshooting work, and identify the issue accurately. The technician can then provide the best solution for the problem.

A furnace system is a complicated machine. Even when it is relatively new, it will succumb to damage, abuse, and overuse. Improper operation can also mean that the furnace is not working optimally and may be pushed to its limit unnecessarily. Some basic DIY steps could work if the problem is simple but they may not be the best solution for a more serious problem, especially for the long term. Keep in mind that the longer you keep your furnace away from professional inspection, the shorter its lifespan will be. Likewise, a small furnace issue will escalate into a larger one, costing you more in the end. Therefore, be sure to address any issues that you notice with your heating system as soon as you notice them.

Another key issue to remember is that a furnace system that is not functioning at its optimal level is a very expensive appliance. You will probably notice this when the utility bills need to be paid. A problematic furnace is an inefficient furnace, which means you will be paying more for power and fuel than you should. The sooner you get your furnace serviced by a professional technician, the better the system will perform.


Heat is essential during the winter months and in most American homes, the furnace is the major source of warmth. There are reasons why the furnace is not working as it should and some of these are easy enough to fix so as not to require the services of a professional. However, some issues do need the skills and knowledge of a trained technician.