Troubleshooting Guide: Furnace Won't Turn On


Troubleshooting Guide: Furnace Won't Turn On

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If you've ever experienced a chilly winter night with no heat, you know the panic that sets in when your furnace will not turn on. The issue of a non-operational furnace can be highly distressing, particularly in the cold winter months. Let’s shed light on the topic and guide you about the various aspects that might be behind your furnace's failure to start, how you can troubleshoot some common issues, and when it may be time to call in a professional for help.

Understanding Why Your Furnace Won't Turn On

Various factors contribute to a furnace that will not turn on, ranging from minor issues to more serious problems that demand immediate repair or even total replacement.

Potential Power Issues

A furnace that will not turn on could be experiencing power problems. The furnace's circuit breaker may have tripped, or there could be a blown fuse. It's also possible that the furnace's power switch, which typically resembles a regular light switch but is located near the furnace, has accidentally been turned off.

Solving Thermostat Troubles

Often, the issue is as simple as a malfunctioning thermostat. Incorrect thermostat settings, dead batteries, or thermostat's internal issues may result in the furnace not initiating.

How to Check Your Thermostat

  • Ensure that the thermostat is set to “Heat.”
  • Check if the temperature setting is higher than the current room temperature.
  • Verify if the batteries need replacement.
  • If it is a programmable thermostat, ensure the schedules are set correctly.

Fuel Supply and Pilot Light

Another reason why your furnace might not be starting could be due to issues related to fuel supply or the pilot light.

Natural Gas Furnace

If you have a natural gas furnace, verify whether other appliances in your home that use natural gas are functioning. If not, get in touch with your gas company. If only the furnace is not working, the gas valve to the furnace might be turned off.

Pilot Light

For older furnace models with a pilot light, the light could have gone out. Instructions for relighting the pilot light are normally printed on the furnace. Do remember: Safety is paramount, so if you are not comfortable doing it yourself, call for professional help.

Ensuring Proper Airflow

A blockage or restriction in airflow can also be a cause behind your furnace failing to operate. This could be due to a dirty air filter or blocked ventilation.

Regularly changing your furnace's air filter is a simple maintenance task that can often be overlooked. A clogged filter restricts airflow and can cause a switch in the furnace to shut off as a safety feature.

Regular maintenance, both DIY and professional, can help you avoid several of these issues and elongate the lifespan of your furnace. If these troubleshooting steps don’t restore your furnace's functionality, it is advisable to get in touch with a heating and cooling professional.

Involve the Experts

Our dependence on the furnace, particularly during the winter season, is significant, so it’s crucial to ensure it is always in perfect working condition. If your furnace will not turn on, and you’ve checked all possibilities mentioned above, it’s probably time to call a professional.

Professional heating contractors have the required knowledge and expertise to assess, diagnose and rectify your furnace problems effectively. They can also perform regular maintenance checks to ensure your furnace runs efficiently at all times, thereby saving you from sudden unexpected issues in the long run.

Remember, your family’s comfort and safety is priority, so don’t hesitate to get professional help for your furnace problems. After all, routine care and timely intervention for your furnace not only enhances its efficiency, but also its longevity.

Frequently Asked Questions About Furnace Will Not Turn On

Why won't my furnace turn on?

The reasons for your furnace refusing to turn on can be multidimensional. These could span from simple power supply issues to complicated mechanical problems. It could be due to a tripped circuit breaker, a faulty thermostat, or even a faulty pilot light. It's also possible that your furnace's inbuilt safety feature might have been triggered and has resulted in its refusal to turn on.

Can a power outage cause my furnace to not turn on?

Yes, a power outage can indeed cause your furnace to not turn on. If your furnace is electric, it will stop functioning entirely during a power outage. Even if it is gas-powered, your furnace still relies on electrical components for operation, and therefore an outage can impact its functioning.

Is it the thermostat that's causing my furnace to not turn on?

A malfunctioning thermostat is one of the common reasons why your furnace may refuse to turn on. If the thermostat isn't working correctly, it may fail to signal the furnace to start even when the temperature drops. Testing your thermostat or replacing the batteries may be a suitable first step in troubleshooting this issue.

Could a blown fuse be the reason my furnace is not turning on?

A blown fuse could very well be the reason why your furnace is not turning on. The fuse is a safety device that blows if an electrical circuit overloads. A blown fuse will disrupt the power supply to the furnace, thereby preventing it from turning on. Do consult a professional to handle this issue to avoid more complications.

Are there any quick fixes I can try when my furnace isn't starting?

While some furnace problems require professional attention, there are a few quick fixes you could try. These include checking the power source and the circuit breaker, replacing the thermostat batteries, resetting the furnace switch or replacing the air filters. It is important to note that these are solutions to common problems. However, if your furnace still refuses to turn on, it's best to consult a professional.

Is it possible that fuel supply issues are causing my furnace to not turn on?

Yes, fuel supply issues could be causing your furnace to not turn on. If you've run out of heating oil or propane, or your natural gas line is shut off, your furnace won't have the necessary fuel to operate. Make sure to check your oil or propane tank levels, or verify your gas supply to ensure this isn't the cause.

Could environmental factors be causing my furnace to not turn on?

Yes, environmental factors can be a reason why your furnace will not turn on. If the area surrounding your furnace is cluttered or has poor ventilation, it might cause overheating, which could lead to the furnace automatically shutting off as a safety measure. Always keep your furnace area clean and properly ventilated.

What do I do if my furnace’s pilot light is off?

If your furnace's pilot light is off, this could be the reason why your furnace will not turn on. You may try relighting the pilot light following the instructions provided in your furnace's manual. However, if the pilot light keeps going off, it's best to call a professional as the problem may be more serious.

When should I call a professional if my furnace will not turn on?

If you've tried basic troubleshooting and your furnace still won't turn on, it's time to call a professional. Also, if you suspect that major components like the thermostat, heating elements, or mechanical parts of the furnace are faulty, do not attempt to fix them yourself. Handling these parts requires professional training and expertise.


If your furnace will not turn on, there are several things you could check like the power supply, the thermostat settings, and the filters. If nothing seems to work after your quick troubleshooting, the problem could be more technical. It might be time to bring in an expert to work on the issue to get your system back in working order.

So, it's clear that a furnace will not turn on for various reasons. It could be due to minor issues like closed or blocked vents, or major ones such as a worn-out motor. But before panicking, remember that some issues are simple to identify and solve, meaning you won't have to incur a hefty repair bill. Always seek to understand what the problem could be; this will save you plenty of headaches down the road.

Facing a furnace will not turn on can be stressful, especially during the cold season. While regular maintenance can help prevent some problems, understanding the potential issues and common fixes can help you quickly get things under control. However, for serious issues, don't hesitate to seek professional help. This will ensure your family's comfort and more importantly, their safety.

About Perfect Air & Water Services

At Perfect Air & Water Services, we've been taking care of Lakewood, NJ's air and water needs with passion and professionalism since our establishment. Located in the heart of Lakewood, we understand local needs better than anyone. Our certified staff is known for going the extra mile to make sure your homes are a haven of clean air and safe water. Want to live in a healthier home environment? Count on us!