There are a wide variety of factors that can contribute to a broken furnace. Signs to look out for include a cold home, a higher heating bill, strange noises, a yellow pilot light, a dirty filter, a tripped carbon-monoxide detector, thermostat problems, poor air quality, or an aging furnace.
What happens when you find out your furnace is broken? It can be easy to panic and stress about what to do, especially during the cold winter months. With a few tested and proven steps, the Boise heating experts at Access Heating & Air Conditioning can get you back up and running in no time. Check out the following signs that may indicate a broken furnace and what you should do to troubleshoot the problem.

Important: If you smell gas, make sure to shut the gas off to the furnace as quickly as possible. Locate the gas meter shut off – usually located next to the furnace and turn it off.

And one final important note: Gas furnaces will produce carbon monoxide during operation. This is a normal part of how they work. When running safely they will exhaust all these fumes to the exterior of the home. But if the furnace is not running correctly this carbon monoxide can get inside the home in rare cases. Make sure you have a licensed heating technician look at your heating system on a routine basis for safety and operation. Having a reputable company like Access Heating & Air Conditioning for your home heating system will be helpful so you never go without a plan during the winter.

Signs That Your Furnace Is Broken

A Cold Home

One of the most obvious ways to tell if your furnace is broken is if your house is getting cold. There could be a wide variety of factors causing this, but most often it has to do with a malfunctioning blower fan. If this is the case, a furnace won’t have enough power to blow air throughout your home, resulting in cold spots. If your furnace isn’t blowing any warm air at all, there could be a problem with the heat exchanger or pilot light. This is something a certified HVAC technician will need to check and repair.

Higher Utility Bills

Another less visible sign of a broken furnace in Boise, Idaho, is a higher utility bill. Treasure Valley homeowners will often see a rise in utility costs as they approach the winter months. However, it’s important to keep an eye on trends and usage for your gas as the temperatures drop. If you see a spike in gas usage on your bill, this can be a sign that your furnace has some sort of intermittent issue.

When your furnace is running harder than designed, the utility bill will start to go up. Often this is a slow and incremental increase over a long time. Check the air coming from your heater vents. If the air feels lukewarm or cold then the furnace is having issues and needs serviced. Most manufacturers have what is known as a “temperature rise”. This determines how much the furnace will heat the air as it passes through the furnace.

In general, the air coming out of the vents during furnace operation will be about 40 degrees higher than the air going into the system. If you have 70 degrees on the thermostat you should see about 120 degrees coming out of the vent registers in the home. This is a general rule of thumb but can provide some basic diagnostic and troubleshooting assistance.

Keep in mind that your furnace will try and maintain a certain temperature within your home at all times. If you have an old, inefficient furnace, it won’t be able to heat your home as quickly as it used to. This can result in it running harder, and longer, using more energy in the process.

Strange Noises

It’s no secret that most furnaces make noise. If yours is generally quiet, you probably have a newer model or it’s located in an area of your home where you can’t hear it. However, if you start hearing strange, unusual noises coming from your furnace, this can be a sign that something needs to be repaired or replaced with your unit.

Yellow Pilot Light

If you have a natural gas furnace, its pilot light should always be blue. If it’s yellow, this is not only a sign of a broken furnace, but it could be leaking dangerous carbon monoxide gas, which can result in serious harm or death. If you notice a yellow pilot light, rust, excessive condensation, or a rotten egg smell, it’s essential to shut off your furnace immediately and contact the Bosie heating experts at Access Heating & Air Conditioning.

Dirty Filter (Or) Ductwork

Every home has a certain amount of dust inside, no matter how often you clean or vacuum. However, if you start to notice more dust than usual, or a large amount of it coming out of your heat registers when your furnace is on, this can be a sign of a dirty filter or ductwork. Signs include floating dust and frequent respiratory problems like coughs and colds. If you or anyone in your family suffers from allergies, the amount of dust particles in the air can cause additional symptoms like watery eyes, itchiness, and headaches. Sometimes, this can be easily resolved by simply changing the filter in your furnace. Other times, however, the ductwork and furnace may need to be professionally cleaned by an HVAC technician.

Thermostat Problems

If you find yourself constantly adjusting the temperature on your thermostat to heat your home, it’s important to have an HVAC technician come out to inspect your furnace and thermostat. It’s possible that the thermostat needs to be replaced or that your furnace can no longer keep up with the demands of your home.


Like all things, nothing lasts forever. This includes your furnace which has an approximate lifespan of 15-20 years. If you have a furnace that’s less than 15 years old, it’s essential to have it properly maintained by a certified HVAC technician every year. If your furnace is older than 15 years, it’s time to start paying close attention to any abnormal sounds, functions, or smells. If you spot any of these concerns, contact the Boise heating experts at Access Heating & Air Conditioning to diagnose the problem and how long your furnace will probably last.

What to Check If You Think Your Furnace Is Broken

First things first, you’ll need to check if your furnace is broken by verifying power. Simply get into your main electrical panel and reset the breaker to the furnace. This will also perform a reset of the system, which can be helpful in the event there is an error. On many newer furnaces, there will be LED lights inside an inspection window on the front of the furnace. You can peek inside and verify those are at least on. Don’t worry though if you don’t see any lights because it may be a model without led lights.

Turn the breaker off and wait 10 seconds and then turn the breaker back on. If you hear any noises or the fan turning on, keep in mind some models like Carrier and Payne will cycle the fan on when there is a power cycle.

Second, you want to verify there is a gas supply to the furnace. Go outside to the gas meter and check if the gas meter outside is turned on. Has there been a service interruption anywhere around your property, recently? Also, check the gas supply shut-off valve inside the house. Sometimes those can get accidentally turned off by someone unaware of what it is.

When in doubt, call your local gas utility company. They can usually troubleshoot if your service is turned off or not. In some cases, they may need to make a house call.

Third, you can do a quick troubleshooting of the thermostat. Make sure the heat button is turned on. If you turn the thermostat off and then back on to heat- you will cycle the power on and off to the furnace. Don’t be concerned BUT sometimes this can clear an error code or temporarily disable a larger issue.

The main thing to consider when your furnace is broken is safety and then restoring operation promptly. At Access Heating & Air Conditioning we provide heating and furnace repair options for all makes and models of equipment.

A lot of Treasure Valley homeowners fear that when their furnace is broken they will be down for days before someone can get to them. We have same-day service throughout our winter months. We are even open on the weekends and all major holidays so homeowners in the Boise and Meridian area don’t have to go without the furnace running.

It can get cold quickly when the temperatures start dropping. So make sure you have a backup plan in place. If you have a gas fireplace- make sure that is operational. A gas fireplace can help take the edge off a cold home.

Access Heating & Air Conditioning

The best plan of action is to be ahead of the curve. Don’t wait until the winter shows up and there is snow on the ground. Contact us by filling out our online form or give us a call at 208-231-8456 to get a yearly tune-up and safety inspection done for your home heating system. As Boise heating experts, our licensed technicians can detect problems and upcoming issues providing you with a plan of action before it becomes a much larger problem.

Helpful Resources
Intermountain Gas Emergency Line


Idaho Power General Help Line


Access Heating & Air Conditioning Emergency Number


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