My Furnace Turns On But No Heat – Why?

woman feeling cold at home checking the thermostat and furnace not heating

Your home offers warmth when the temperatures outside plunge. All you have to do is turn on your furnace to heat your indoor air. It is a reliable system that typically works well, but there may be times that it encounters an issue, so it doesn’t operate as it should. For example, what if the furnace turns on but no heat? This is a common problem, and many homeowners become frustrated, especially if the indoor temperature plummets fast. Being level-headed will let you assess each of the likely causes.

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Why Am I Not Getting Any Heat When My Furnace Is On?

The simple fact that your furnace still switches on is beneficial. It signals that the power supply is in good working condition. However, something else within the system may keep it from working properly. The problem may be a simple oversight that needs some quick tweaking for the unit to get back to proper working order. This is typically the case, so you don’t have to panic. If the issue is more complex, you can leave it in the capable hands of a licensed HVAC contractor.

Read on to learn the most common causes of a furnace that is not producing heat even when turned on. Some of these are incorrect thermostat settings, airflow problems, furnace ignition problems, and insufficient fuel.

This article includes what can go wrong in these areas. It also contains basic furnace troubleshooting so the unit can be set straight. Every homeowner can do these simple measures. With luck, your furnace will return to operation so you can put its issues behind you. However, if the furnace remains unresponsive even after performing a furnace inspection, call an HVAC professional for help. Learn from this experience as well. This way, you can keep the problem from recurring.

Problems at the Thermostat


Furnaces are built to operate as instructed. If your intention and instruction to your furnace differ, you will receive unexpected results. The thermostat is your heating system’s control center, so you need to be sure that you input the correct information. For example, you may have wanted your heating unit to produce warm air but haven’t set the thermostat yet to trigger heat production. In this case, your furnace isn’t really malfunctioning as you only need to change the thermostat to match your heating goals. The thermostat may be set to COOL, so you must change it to HEAT.

Someone in your house may have adjusted it while you were away and forgot to turn it back. Never assume that the settings in your thermostat are correct. Take your time to check it first.
The fan settings should be checked as well. Many homeowners think that a moving fan means the furnace produces and distributes heat. However, this doesn’t always happen. A fan set to ON means it will run all the time, even when the furnace isn’t in a heating cycle. It is better to set the fan to AUTO, so it will only run during heating cycles, ensuring that only heated air is forced through the vents. You can also opt to set your thermostat higher by around five to ten degrees. This will help you feel a noticeable difference. Call a professional HVAC technician if cold air from your furnace persists even after doing these steps.

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Problems With Furnace Airflow

Air should be able to travel freely throughout your furnace so that the unit operates properly. Airflow issues can result in the heat being unable to travel from the system to each room. Heat may not be coming out of your furnace due to an obstruction stopping the flow of air. Some of the common causes of this problem are:

The Furnace Air Filter Is Dirty

senior man changing a dirty air filter in an hvac furnace

Air filters capture airborne debris, such as dirt, pollen, dust, and pet dander. They are crucial components as they keep the ductwork and furnace interior from becoming dirty. However, they tend to accumulate gunk over time. As a result, the filter’s surface becomes covered in a thick layer of dirt that blocks the air from freely passing through them.

The best approach homeowners can take is to perform monthly air filter checks. This way, they can see when they need to replace it. Many can follow the manufacturer’s replacement schedule but keep in mind that several factors affect when is the best time to replace their furnace air filters. Some homes may need a more frequent filter change than others, especially if the area they live in tends to have a lot of dust or if they have a lot of pets.

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Fallen Debris & Other Obstructions

Items may have fallen into the heater vents. If so, they need to be removed. Take off the vent covers and use a flashlight to see. Remove any objects you can reach immediately. Use a pair of gloves to be safe if you are unsure what you are retrieving. You can try using a long wire or stick for any items that are hard to reach.

Some Of The HVAC Vents Are Closed

image of a closed hvac air vent

The problem may be as simple as a few closed vents. Walk around your home to ensure that all louvers are open. Make adjustments when needed. The louvers may have gotten stuck, so remove the vent covers and clean them from time to time. Jammed covers may need to be replaced.

Moreover, ensure that the registers or vents are not blocked. Someone may have moved furniture, causing a block to a vent. Remove these blockages to ensure good airflow again.

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Furnace Ignition & Fuel Problems

image of a heating system depicting a furnace pilot light and furnace fuel supply issues

Furnaces that switch on but do not generate heat may be low in fuel. A furnace that doesn’t have an energy source will not be able to accomplish anything. If the furnace is gas-powered, check that the gas valve is open and verify that there is no interruption with your gas company. If the line service was interrupted, determine when it will be restored.

On the other hand, determine how much fuel is left if you have propane- or a heating oil-powered heating system. Book a delivery if necessary. Monitor your fuel levels to keep this problem from happening again. You should also be mindful of your fuel usage on a regular basis. You can also install monitoring devices to keep track of your fuel levels for you. The heating oil company can also handle the fuel level monitoring for you, so you receive timely refills.

When you are certain you have plenty of fuel, the ignition system may be causing the problem. The ignition system is responsible for starting the fuel combustion. Your furnace cannot generate sufficient heat if it doesn’t work properly. If you have an older model, ensure it has a lit pilot light. Otherwise, follow the manual’s instructions on how to relight the pilot light. If you have a newer model, check the ignition switch located in the electronic ignition system. Carefully wipe away any dirt on the metal strip before retesting the ignition.

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Having a furnace that turns on but doesn’t generate heat can be confusing. Learning the best troubleshooting steps to take can help you the next time you face this problem. If the tips mentioned in this article do not work, consult a professional HVAC technician. These licensed professionals are equipped with the tools, skills, and training to handle complex issues your furnace may have. They can provide accurate and quick diagnoses and apply the best solution to your furnace problems.

Call Point Bay Fuel For All Of Your HVAC Requirements


Point Bay Fuel offers superior heating and cooling services in Ocean and Monmouth County, New Jersey.

Our certified technicians can provide you with excellent HVAC services, including heating and cooling tune-ups, repairs, installations, and replacements. Each technician has outstanding knowledge and experience to serve your HVAC system needs correctly the first time around.

Point Bay Fuel guarantees to provide the most competitive heating and cooling service costs in the area. Our maintenance services ensure to improve your comfort, increase your system’s energy efficiency, and reduce your home’s heating and cooling costs.

Need your system repaired or replaced? We’ll recommend the best solution that works well within your budget. The best part is, all our work is backed with a guarantee to ensure your satisfaction.

If you wish to schedule a service appointment, give us a call today!

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