Six Warning Signs That Your Furnace May Be Failing

Article Found on Modernize

Have you ever woken up freezing on a cold winter’s night? If you haven’t accidentally left the window open, chances are your furnace has broken down—and it can be a couple of miserably chilly days to wait while your furnace is repaired or replaced. However, if you can diagnose a failing furnace before it actually goes out, you can call a technician to repair or replace the unit without having to wait in the cold! Here are a few helpful warning signs that your furnace could be taking its last breath.


Although it would be nice if your furnace lasted forever, its average lifespan is between 15 and 20 years. If you’ve had your furnace for less than 15 years, make sure you do proper maintenance according to the manufacturer’s specifications. Once your furnace reaches 15 to 20 years of age, it’s time to start paying close attention to any abnormal functions, sounds, and smells. If any of these occur, call a qualified technician to diagnose the problem—they can tell you about how long your furnace will last.

Cold Air

It might seem obvious, but a furnace that’s not heating your home is a warning sign of imminent furnace failure. It could be a number of different problems causing this, but most often it has to do with the motor in the blower fan. If the blower fan is malfunctioning, the furnace doesn’t have enough power to blow air throughout the home. This can cause cold spots in some parts of the home. If your furnace isn’t blowing any warm air at all, it may be a problem with the heat exchanger or pilot light. This is something a qualified technician will need to to take a look at, to see if there’s any repair that can be completed.

Strange Noises

It’s pretty obvious that HVAC systems make noise. If yours doesn’t, you probably have a brand-new model, or it’s hidden somewhere in your home where you can’t hear it. However, if you start hearing pops or squeaks, it may indicate that something has come loose in your unit and needs to be repaired or replaced.

Increased Heating Bill

Are you using your furnace consistently and yet your heating bill has increased substantially? This can be another warning sign that your furnace is on its last leg. Furnaces try to keep a certain temperature within the home at all times. If the furnace isn’t efficient enough to heat the home as quickly as it used to, it may run longer, using more energy.

Yellow Pilot Light

If you have a natural gas furnace, go and check the pilot light—which should always be blue. If the light is yellow, it’s not only a warning sign that your furnace needs repairs, but that your furnace could be leaking carbon monoxide, a poisonous gas. If you notice a yellow pilot light, excessive condensation, rust, or a rotten egg smell, shut off your furnace immediately and call an HVAC technician.


There’s always going to be a certain amount of dust in a home, no matter how often you dust off your furniture. However, if you notice an unusual accumulation of dust—or a large amount of it coming from the heat registers when the furnace kicks on—it could be your furnace telling you that it’s ready to give up the ghost. Your furnace takes dirty outside air, filters it, heats it, and blows it throughout your home. As your furnace gets older, it has a harder time filtering. Of course, you should change your filters every one to three months, but it’s not just your furnace filter that helps to clean your air. Your ductwork and blower fan also help to filter your air. If you notice an excess of dust, call a certified technician.