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Ask John Faulty Furnace Main Image

Why Isn’t My Furnace Turning On?

John Turpin is our resident home service repair expert here at Service Direct. He’s got the knowledge and experience to help homeowners like you make sense of most home repair issues. And with Service Direct, we connect you with top-tier service professionals to help with any repairs needed.

Don’t Panic If You Find Your Furnace Is Not Turning On

It’s been cold the past few days, so you thought of using the furnace but it wouldn’t work when you tried. Now you’re concerned and wondering, “Why isn’t my furnace turning on?” You’re understandably frustrated, knowing how important a properly functioning furnace is in maintaining a warm and comfortable home during the colder months.

Several factors can contribute to a furnace not turning on, ranging from simple operational problems to more complex technician issues. Ideally, a professional should inspect your furnace for a quick and effective repair but you can troubleshoot it as well. On that note, we’re here to explore some common causes and possible solutions you can try to resolve this problem.

Common Causes and Possible Solutions to a Furnace Not Turning On

Thermostat Issues

One possible reason behind a furnace not kicking on when the temp drops is a problem with the thermostat. The thermostat acts as the control center for the furnace, signaling it when to turn on or off based on the desired temperature settings. Issues with the thermostat can disrupt this communication and prevent the furnace from starting.

To fix it, start by checking the thermostat settings. Ensure it is set to the desired temperature and switched to the “heat” or “auto” mode. If it’s battery-powered, replace the batteries to rule out any power-related issues. You can also try to reset the thermostat by turning it off for a few minutes and then turning it back on.

Power Supply Problems

If your furnace is not receiving power, then it won’t turn on. Power supply issues can stem from various sources, such as a blown fuse, a tripped circuit breaker, or a malfunctioning power switch. If you suspect your furnace isn’t turning on due to power supply problems, try fixing it starting with checking the circuit breaker panel or fuse box to see if any breakers have tripped or fuses have blown.

Once you confirm there are blown fuses or tripped circuit breakers, reset or replace them as needed. Additionally, check the power switch located near the furnace to ensure it is in the “on” position. If these steps don’t resolve the issue, consult a professional to inspect the electrical connections and diagnose any underlying wiring or power supply issues.

Furnace Not Turning On
There are many variables that can cause your furnace or AC to malfunction.

Pilot Light or Ignition Problems

If your furnace won’t turn on but the fan works, one of the possible causes has to do with the pilot light or ignition. A malfunctioning pilot light or ignition system may result from a gas supply problem, a defective ignition control, or a faulty thermocouple. If your furnace has a pilot light, find out if it’s the issue by checking if it’s lit.

In case the pilot light is not lit, follow the manufacturer’s instructions to relight it. As for furnaces with an electronic ignition system, listen for the clicking sound indicating an attempt to ignite. If you don’t hear the clicking sound, there may be an issue with the ignition system that needs professional attention.

In both cases, if you suspect a gas supply problem or a faulty thermocouple, it’s crucial that you contact a professional technician to inspect and repair the furnace safely.

Clogged Air Filters

Dirty or clogged air filters could be one of the reasons behind a furnace not turning on automatically. If the air filters are dirty or clogged, they can restrict airflow and cause the furnace to overheat. It triggers a safety feature that shuts off the system, preventing the furnace from turning on or causing it to cycle on and off frequently.

You can troubleshoot it by inspecting the air filters and replacing them if they are dirty or clogged. Air filters are typically replaced every 1 to 3 months, depending on the type of filter and usage. Regularly changing the filters ensures proper airflow, reduces strain on the furnace, and helps maintain its efficient operation.

Our resident home repair guru, John Turpin, discusses why your furnace isn’t turning on, along with some suggested solutions and DIY tips to address it.

Gas Supply Issues

For gas-powered furnaces, a lack of gas supply can prevent the furnace from turning on. Gas supply issues can stem from various problems, such as a closed gas supply valve or an issue with the gas line. For this issue, ensure that the gas supply valve near the furnace is fully open. If it’s closed, open it and wait a few minutes before attempting to turn on the furnace again.

If the gas supply valve is open but the furnace still doesn’t turn on, or if you detect a gas leak or a strong gas odor, evacuate the premises immediately. Once you and your family are out, contact your gas utility provider or emergency services right away.

Faulty Blower Motor or Capacitor

The blower motor is responsible for circulating warm air throughout your home. If its associated capacitor is faulty, that could be why your furnace is not turning on, or blowing air properly. You’ll have an idea that this might be the case if you don’t hear the sound of the blower motor running when the furnace should be operating.

This could mean something’s wrong, which is best handled by a professional. Consult an expert technician to inspect the blower motor and its capacitor, as they may need to be repaired or replaced to restore proper functioning.

Furnace Ducting Issues
Regular maintenance helps prevent furnace issues and resolve problems before they exacerbate.

Blocked Vents or Registers

Blocked or closed vents and registers can restrict the airflow, causing the furnace to shut off or not turn on at all. Common causes include furniture or objects obstructing the vents or registers, or accidentally closing them.

It’s easy enough to resolve this – check all vents and registers throughout your home to ensure they are open and unobstructed. Remove any furniture, rugs, or other items that may be blocking the airflow. This allows for proper air circulation and ensures the furnace can operate efficiently.

Lack of Regular Maintenance

A lack of regular maintenance can contribute to various problems that may lead to the furnace not turning on. Dust and debris accumulation, worn-out components, and neglected repairs can lead to operational issues. This makes it crucial to have your furnace maintained regularly, allowing you to keep it in optimal condition.

Schedule regular maintenance and let professional technicians perform thorough inspections. Let them clean components, lubricate moving parts, and address any potential issues before they escalate. Regular maintenance helps keep your furnace running efficiently and reduces the likelihood of unexpected breakdowns.

Faulty Furnace FAQs

Can I fix a furnace that doesn’t turn on by myself?

While there are some troubleshooting steps you can take, such as replacing air filters and checking thermostat settings, it’s recommended to seek professional help for accurate diagnosis and repairs. Furnaces involve complex electrical and gas components. Improper handling of these components can lead to safety hazards or further damage to the furnace.

Is it normal for a furnace to have a delay before turning on?

A slight delay before the furnace turns on can be normal, as the system goes through its ignition sequence. But if the delay is excessive or if the furnace doesn’t turn on at all, it may indicate an underlying issue. Your furnace may require attention from a professional technician.

How much power does an electric furnace need?

In general, electrical furnaces need 10,000 to 50,000 watts (W) of electricity to work, but it all depends on the model. On average, standard residential homes that use electrical furnaces use around 20,000 W. Most electric furnaces need between 60 and 80 amps of electricity, connecting to a 220-volt breaker.

Hire a Local HVAC Expert

When faced with a faulty furnace that you can’t troubleshoot or fix yourself, our HVAC contractors are standing by to help with diagnosis and repair. Reach out to our local technicians anytime using the phone number or form on this page.

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