My Furnace Turns On But No Heat – Why?

image of a homeowner feeling chilly due to furnace turns on but no heat

Your home is a warm retreat when the outdoor temperatures drop. You can switch on the furnace and enjoy warm indoor air. It is a reliable home heating system that typically works effectively. However, you may wonder what will happen if the system fails to do its job. At some point, you may find that turning on your furnace may not generate the warm air you would expect. It is a common issue, and many consumers become frustrated over this problem, especially as the indoor temperature plunges fast. However, a level head will let you perform some furnace troubleshooting to help you find the likely reasons for this heating issue. Keep reading to explore why a furnace turns on but no heat.

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

It is a good sign that your furnace still turns on because this indicates that its power supply is in good working condition. However, something may be keeping your furnace from working as expected. The problem may be due to a simple error that needs a quick adjustment to get it back in working order. This is typically the case, so you don’t need to panic. Call a licensed HVAC technician for professional assistance if the issue is more complex than you can handle.

Read on to learn the most common causes for a furnace that isn’t producing heat when turned on. These include incorrect thermostat settings, airflow issues, not enough fuel, and furnace ignition problems.

This article discusses what can go wrong in these areas and how you can troubleshoot them properly. Every homeowner can do these basic steps. With luck, your furnace will be back up and running in no time. However, if your furnace problem persists after troubleshooting, call a reputable HVAC company to assist you.

Problems at the Thermostat

image of a homeowner adjusting a programmable thermostat

Furnaces were designed to perform based on the instructions the thermostat gives them since it controls the entire heating system. Therefore, you need to make sure the thermostat is correctly. You would be surprised how many heating issues are caused by an improperly set thermostat. Naturally, a furnace won’t perform as expected when you haven’t set the thermostat to start heat production. If this is the case, there isn’t a problem with your furnace as you only need to change the thermostat settings to achieve your heating needs. For example, the thermostat may be set to COOL, so you have to change it to HEAT. Someone in your home may have also changed the thermostat without your knowledge. Never assume that the settings on your thermostat are correct. Make sure you always check the basics.

The fan settings should also be checked. Many homeowners think that a moving fan means the furnace generates and circulates heat even when it isn’t doing a heating cycle. Instead, set the fan to AUTO so that the fan only runs during heating cycles. This way, only warm air is pushed through the vents. You can also input higher temperatures into your thermostat. Try raising it to around 5 to 10 degrees so you’ll feel a noticeable difference. However, call a licensed HVAC technician if your furnace still only produces cold air after doing these steps.

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Problems With Furnace Airflow

Air must flow freely through the forced-air HVAC system to operate properly. If there are airflow issues, the heat cannot travel from the furnace to each room. An obstruction may block the airflow and stop the furnace from circulating heat properly. Here are some of the common culprits behind this issue:

The Air Filter Is Dirty

image of a dirty furnace filter and homeowner replacing it

Air filters are crucial furnace components for catching airborne pollutants like dirt, pollen, and pet dander. They keep the furnace interior and ductwork from becoming dirty. As a result, the furnace filter ends up with gunk build-up. Their surfaces eventually become so covered with dirt and other debris that air cannot move freely through them.

Homeowners should make it a habit to conduct monthly air filter checks. This way, they can replace their filters before it negatively affects their system. It is important to note that manyny homeowners can replace their filters per the recommended schedule of the manufacturer. However, several factors can affect when is the best time to do furnace filter replacements. For example, if you have a lot of pets, you need to change the filters more frequently. Check monthly and replace when needed.

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The HVAC Air Vents Are Closed

Some vents may be closed. Make sure that louvers around your home are open. Adjust them as needed as well. They may get stuck, so you should remove the vent covers for periodic cleaning. If they are jammed, the covers may need to be replaced. You should also ensure that there are no blockages to the air registers and vents. Someone may have moved furniture and blocked a vent. Remove these blockages so there is good airflow again.

Fallen Debris & Other Obstructions

image of an hvac air vent

Items may have fallen into the heater vents. Remove the vent covers and use a flashlight to see inside. Take out any objects that are within reach right away. Use gloves to ensure your safety if you are unsure of what you have to take out from the vents. Use a long wire or stick to help you if the objects are hard to reach.

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Furnace Ignition & Fuel Problems

gas furnace flames

Low fuel can be the reason behind a furnace that turns on but doesn’t produce heat. A furnace cannot operate without an energy source. Check if the gas valve is open if you use gas. Contact the gas company to ensure there are no service interruptions as well. If this is the cause, determine when the service will come back again.

If you rely on propane or heating oil, check the fuel levels in your tank. Book a refill when needed. Monitoring how much fuel you have left can help stop this problem from happening again. It also helps if you are mindful of the fuel amount you use regularly. You can also opt to use monitoring devices to track your fuel levels. Another option is to use automatic fuel delivery, where the propane or heating oil company monitors your fuel levels for you. Likewise, they will schedule a delivery when your tank is 30% full.

If you do have plenty of fuel, you might be dealing with an ignition system problem. The ignition system is what starts the fuel combustion. A faulty ignition system means the system cannot generate enough heat. If you have an older model, check the pilot light. If it is not lit, check the manual and follow the instructions regarding relighting the pilot light. If you have a newer model, inspect the ignition switch in your heater’s electronic ignition system. Dirt on the metal strip must be carefully cleaned before the ignition is retested.



A furnace that doesn’t heat your home can cause some confusion among the occupants. This article includes useful information on the issue. This helps you the next time you encounter this problem because you know the best troubleshooting measure to take. Call an HVAC professional when the tips mentioned above don’t work. Certified HVAC technicians have the right tools, skills, and extensive training to deal with your heating system’s complex problems. They can accurately and quickly diagnose the source of the issue and apply the best possible solutions.

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Wilcox Energy provides high-quality heating and cooling services throughout the southern Connecticut shoreline. We have the best professionally certified and highly skilled technicians for all your HVAC service needs, such as maintenance, installations, replacements, and repairs. All our techs can service your HVAC system correctly using their knowledge and experience.

Our company offers highly affordable HVAC service rates in the locality. Our tune-up services help you achieve higher energy efficiency and better home comfort with reduced energy costs. If you need to replace or repair your HVAC system, we can recommend the most suitable and budget-friendly one for your home. Your satisfaction is important to us, so all our work is guaranteed. Call Wilcox Energy to schedule a service appointment today. We offer free, in-home estimates.

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For more information about our HVAC services, be sure to contact Wilcox Energy. You can click here to contact us, or you can call us at (860) 399-6218 to find out more. We offer a full line of heating and cooling repairs, maintenance services, and installations.