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Your Furnace Isn’t Turning On? Here is What To Do

Written by Vaughan Comfort Services on . Posted in .

With temperatures expected to drop below freezing many days this winter, having your furnace break at the last minute can be frustrating, stressful, and even scary for homeowners. When your furnace breaks, it can lead to costly damage to your home from frozen pipes to cracks in your windows and even structural damage. That doesn’t even begin to touch the concerns about you and your family staying warm during the coldest period of the year.

Read this information about the most common furnace problems and some furnace troubleshooting tips. If your HVAC system issues run deeper than a quick DIY fix, call the service experts at Vaughan Comfort Services at 856-627-0303 or use our online form to schedule a furnace repair appointment.

How Does a Furnace Work?

Your furnace is a complex machine with many parts including a blower motor, flame sensor, pilot light, power switch, ignitor, thermostat, air ducts, and many others. A thermostat in your house (or several, if you have zoned heating) measures the temperature to control the heating cycle. When the temperature drops below the set target, the control board receives a signal that tells the furnace to open the gas valve and turn on the electronic ignition. This ignition lights the burners.

The furnace flame sensor, in turn, ignites the blower motor, which cycles the heated air through your air ducts to warm your home. Gasses from the combustion then travel through your heat exchanger into the flue pipe where they exit your home.

This is the short version of how a basic forced-air gas furnace works. There are many different types of cooling and heating systems including heat pumps, heat exchangers, ductless systems, and others.

Why Won’t My Furnace Turn On?

There are several reasons why your furnace may not turn on. The most common include a broken thermostat, gas line issues, clogged air filters, blocked ductwork, a tripped circuit breaker, and issues with the furnace itself. The more minor issues are as follows.

Your Thermostat Has an Issue

A bad thermostat can create all sorts of issues with your furnace. It can fail to detect the room setting properly and thus not tell your furnace to kick on. It can have electronic problems that fail to send signals to the control board, preventing furnace ignition. Improper programmable thermostat settings may prevent your furnace from starting.

If your thermostat is broken, it may need to be replaced. Most electronic thermostats will display an error code when something goes wrong. You can check this error code to see if there is an easy fix, like a reset. If it is not something simple, a replacement is in order. You may be savvy enough to do this yourself, but if working with electrical components concerns you, an experienced HVAC technician can usually do the job quickly.

Your Gas Is Not Turned On

If you have a natural gas furnace, the gas line and gas valve are essential to its proper operation. A lack of gas supply to your furnace can mean a wide range of things. It could simply be that your gas valve is turned off, in which case opening the valve can fix the issue. It could be that your gas lines are clogged, or you have a gas leak, in which case you should immediately get out of the house and call for help. Leaks in your gas supply can be dangerous and deadly.

Many modern furnaces have a safety switch or other safety features designed to shut down the furnace in case of a gas leak. If you smell gas or cannot figure out why your furnace does not seem to be getting gas, you should immediately put in a service call to a qualified plumbing and HVAC expert.

You Need to Replace Your Air Filter

Man wearing a mask changing an air filter

Some smart thermostats have safety systems that shut off the furnace or alert you in case of a dirty air filter. Fortunately, troubleshooting a dirty furnace filter is one of the easiest furnace maintenance tasks to do. In fact, changing your furnace filter is something you should do roughly four times a year. Many HVAC repair service technicians recommend doing it at the changing of seasons to make it easy to remember.

Changing the air filter is a step-by-step process:

  1. Locate the air filter.
  2. Open the access panel, which in some models can be as easy as sliding a plate off. Other models may require a screwdriver, but you should not need any specialized tools.
  3. Pull out the old furnace filter.
  4. Slide in a new air filter.

Your Ducts Are Blocked

Blocked ductwork can present a danger to your home as pressure can build up, and the clogging, buildup, and blockage from dust, dirt, and other particles can not only limit airflow, but can present a fire hazard. Duct cleaning should be a part of your regular furnace maintenance, but it is not something that is easily done by yourself. You should speak to your heating, ventilation, and air conditioning technician about checking ducts at least once a year, if not more often.

Your Circuit Breaker Tripped

A tripped circuit breaker has an easy fix, but it can also be indicative of a bigger electrical problem. If your furnace’s power usage overrides your available circuits, it may be too big for your house, you could need to devote more power from your box to the furnace circuit, or you may have a more serious electrical problem. Only experienced technicians should deal with whole-home electrical issues.

You can usually turn the furnace back on just by checking your main circuit box, locating the tripped breaker, and flipping it back to the “on” position. It is a good idea, however, to schedule a service call to ensure that you do not have more serious issues.

More Serious Issues With Your Furnace

As stated above, your furnace comprises many different parts and safety features. A malfunction in any part of a safety trigger can cause your furnace to shut down. Some of the most common issues with furnace components follow.

Your Furnace Power Switch Is Off

Just like any appliance, your furnace has a power switch. It is usually not easy to shut it off by accident, but it may happen. If the power switch is off, you may be able to restore service simply by turning it back on. In some cases, however, a safety trigger may have caused it to shut down. If the power switch randomly shuts off, contact an HVAC system professional to check things out.

The Flame Sensor Is Dirty

A dirty flame sensor is often an easy fix. If the flame sensor cannot detect the pilot light for the furnace, the entire system can shut down. You may not even need a new sensor; a qualified technician may be able to clean the one you have. It is not easy to access, however, and is a sensitive piece of electronics, so a qualified HVAC service professional should address the issue.

Your Capacitor Has Failed

A capacitor is an electrical component that helps run the blower motor. When this fails, the motor cannot run, and the furnace will not fire up. Qualified furnace technicians can test the capacitor and replace it if need be.

Safety Features Are Triggered

Your furnace has many safety features, and any that are triggered or malfunction can stop your furnace from starting. A few of these safety features include:

  • Safety float switch: The safety float switch monitors the condensation drain pan on HVAC systems and shuts the system down if the tray gets too full.
  • High-limit switch: The high-limit switch communicates with your thermostat to maintain the proper temperature. It is in place to ensure that your furnace does not overheat.
  • Pressure switch: The pressure switch shuts off your system if it detects flue gasses that have not been exhausted from your home.
  • Flame roll-out switch: The flame roll-out switch shuts down your system if it detects flames escaping the furnace combustion chamber.

Furnace Blower Motor Issues

The furnace blower motor is what circulates warm air throughout your house. Along with the thermostat, it is the heart and soul of your HVAC system. If problems exist with the furnace blower motor, the entire system cannot work.

Open or Broken Furnace Door

Your furnace door must be shut to maintain the proper pressure and conditions inside. The furnace has a furnace door switch that will ensure that the furnace cannot operate if the door is open or unhinged.

When Should I Call a Professional to Fix My Furnace in New Jersey?

Vaughan Comfort Services offers expert, experienced furnace repair services in New Jersey. It is a good idea to have your furnace checked and cleaned and to perform routine maintenance at least once a year, if not twice or more often. Exactly how often your furnace needs to be serviced depends on its age, size, the complexity of the system, and many other factors.

The best option is to put in a service call and have the experts at our company take a look. We can recommend an ideal maintenance routine to keep you running with reliable service and avoid major issues.

How Do I Avoid Issues With My Furnace This Winter in New Jersey?

To avoid issues this winter, we recommend scheduling routine maintenance. The service experts at Vaughan Comfort Services can handle any level of maintenance or repairs. If your furnace is very old, it may be advisable to consider replacing it. A replacement furnace can save you money in the long run by being more energy efficient and requiring less maintenance and fewer repairs. Your HVAC technician can provide options if this is necessary.

Freezing Temperatures Can Damage Your Home. Call Our Experts Before It’s Too Late

Call our service experts at 856-627-0303 or fill out our online contact form to get your furnace repaired as soon as possible. We offer emergency services when freezing temperatures present a health and safety risk. Don’t freeze this winter. Get in touch with Vaughan Comfort Services to make sure your family and home stay warm and safe in the coldest months of the year.

NJ LIC. NO.13VH01727600
Robert W. Vaughan,
Master HVACR Contractor Lic. # 5842
Thomas J. Weaver,
Master Plumber Lic # 9521

Contact Info
212 Barrett Avenue
Magnolia, NJ 08049

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