Like millions of American homeowners, you depend on your furnace to keep your home warm during the cold winter months. When your furnace malfunctions, it can be frustrating, uncomfortable, and costly if not addressed quickly. Fortunately, many common furnace issues have simple solutions that you can handle on your own or with professional help. Let’s look into the most common furnace problems and the steps you can take to troubleshoot them effectively.
Thermostat Problems
One of the most common furnace issues originates from the thermostat. If your furnace isn’t working properly, the first thing you should check is the thermostat. If the display is blank, it could be due to a power issue. Start by checking your circuit breaker to ensure nothing has tripped. If the breaker looks fine, inspect the thermostat batteries, if it has them. Dead batteries are often an overlooked cause of a thermostat that won’t function.
If replacing the batteries doesn’t solve the issue, loose wiring or a faulty thermostat might be the culprit. Wiring problems can cause inconsistent communication between the thermostat and furnace and lead to heating inconsistencies. While it might be tempting to attempt a fix yourself, it’s often safer to consult a professional HVAC technician who can inspect the wiring and replace a malfunctioning device if needed.
Short Cycling
Another issue homeowners frequently encounter is short cycling, where the furnace turns on and off rapidly without completing a full heating cycle. Short cycling can cause your home to feel cold and prevent your furnace from running efficiently. The most common cause of this problem is a dirty air filter. Over time, dust, dirt, and other debris can accumulate in the air filter and obstruct airflow. This restricted airflow causes the furnace to overheat and triggers its internal safety mechanisms to shut it down.
Fortunately, replacing the air filter is a simple fix. Most HVAC professionals recommend changing the filter every three months, but if you have pets or live in a dusty area, more frequent changes might be necessary. Be sure to use the right filter for your system because filters have different levels of filtration, and using one that’s too restrictive can reduce airflow even when it’s clean. If short cycling continues after replacing the filter, it may indicate more serious issues like improper furnace sizing or issues with the thermostat, both of which should be addressed by a professional.
Pilot Light Issues
Older furnaces often rely on a pilot light to ignite the burner. If you notice that your pilot light is weak or has changed color (especially if it’s yellow instead of blue), it’s time for a closer inspection. A yellow pilot light can indicate poor combustion, which could be caused by an obstruction in the fuel supply line or a buildup of soot, rust, or oil on the burner.
You should always be cautious when dealing with pilot light issues. A malfunctioning pilot light can cause incomplete combustion, leading to the production of carbon monoxide—a dangerous, odorless gas. If you suspect a problem with your pilot light, it’s best to turn off the system and call a professional to clean or replace the burner, check the gas line for blockages, and ensure the flame is burning properly.
High-Pitched Squealing
A high-pitched squeal coming from your furnace is a sure sign something’s wrong, and it’s usually related to the blower fan. Most often, the cause is a worn-out or loose blower belt. As the belt wears down, it starts to fray or slip and will cause that unpleasant squeal. If you catch the problem early, replacing the belt is a straightforward job that can prevent more considerable damage to the blower motor.
Blower Fan Running Continuously
If your furnace’s blower fan is running non-stop, even when the furnace isn’t heating, it’s likely an issue with the limit switch. The limit switch tells the blower fan when to turn on and off, based on the furnace’s internal temperature. A malfunctioning limit switch can cause the blower to run continuously, wasting energy and putting extra strain on the motor.
In some cases, this issue can be resolved by adjusting the fan setting. Make sure it’s set to “Auto” instead of “On.” If the fan is still running non-stop, it’s a sign the limit switch is defective and needs to be replaced. This is another situation where professional help is recommended, as dealing with internal furnace components can be dangerous for those unfamiliar with the system.
Ignition Problems
When your furnace sparks but doesn’t ignite, it can be frustrating, especially when the house starts to cool down. This issue is often related to the thermocouple, a small safety device that senses when the burner flame is lit. If the thermocouple is dirty or faulty, it won’t allow gas to flow to the burner.
A dirty thermocouple can often be cleaned with a soft brush, but if the problem persists, it may need to be replaced. Since the thermocouple plays a critical role in safely controlling gas flow, it’s important to address this issue quickly and correctly. A licensed HVAC technician can replace a faulty thermocouple and ensure your system is operating safely.
Gas Leaks
If you smell gas in your home, it’s a serious problem that requires immediate action. A gas leak smells like rotten eggs or sulfur, and it can lead to dangerous situations like fires or explosions. If you suspect a gas leak, shut off the gas supply to your furnace and open windows to ventilate the area. Leave the house and contact a professional right away.
No Air from Vents
When your furnace is running but no air is coming out of the vents, the problem is likely a malfunctioning blower motor. The blower motor is responsible for circulating warm air throughout your home, and when it fails, heat stays trapped in the furnace. If this happens, you’ll need to have the motor repaired or replaced to restore proper airflow.
In some cases, this issue can be caused by a blown fuse or a tripped circuit breaker, so it’s worth checking those first. However, if the motor itself is the issue, professional replacement is the best solution.
Uneven Heating
When some rooms in your home are warmer than others, your furnace may not be distributing heat evenly. First, check that all the vents are fully open in each room. If they are, the problem might be with your ductwork. Obstructions or leaks in the ducts can prevent warm air from reaching certain areas of your home.
Hiring a professional to inspect and clean your ductwork can often solve this issue. If necessary, they can seal any gaps or repair damaged ducts to ensure even heating throughout your home.
Unusual Smells
It’s normal for your furnace to emit a slight burning smell when it first starts up for the season, as it burns off dust that’s accumulated. However, other smells—such as musty, metallic, or electrical odors—can indicate serious problems.
A musty smell could mean there’s mold growing in your ductwork, while a metallic or burning electrical odor might point to overheated wiring or components. In either case, it’s important to shut off your furnace and call a professional to inspect it. Continuing to run the furnace could lead to more extensive damage or even an electrical fire.
Water Leaks Around the Furnace
High-efficiency furnaces produce condensation as part of their operation. Normally, this condensation is drained through a pipe. If you notice water pooling around the base of your furnace, it’s likely that the condensate drain is clogged or leaking.
Clearing a clogged condensate line is usually a simple fix. Blowing out the line can remove any debris causing the blockage. If the drain is leaking, however, you may need to call a professional to ensure the problem is properly repaired.
Exceptional Furnace Service
At Aurora Pro Services Heating, Air, Plumbing, Electrical, & Roofing, we provide expert furnace services to homeowners in the Greensboro, NC area. Whether you’re facing heating problems or need routine maintenance, our experienced technicians are here to help. From fixing minor issues to handling major heating repairs, we ensure your furnace is running efficiently. Contact us today to schedule your service.
