Troubleshooting Your Furnace: 9 Common Furnace Problems and Effective Fixes

Do you dread the first chill breeze of fall and winter? Maybe because you know you’ll soon be dealing with your furnace again. In addition to being notoriously finicky, it’s also the most common source of home heating problems. Unfortunately, no mechanical device is immune from breaking down from time to time. The good news is that a busted furnace is not a sign that your home will become uninhabitable for the next few months. With some simple troubleshooting and repair techniques, almost any furnace can be brought back to life again. So if you’re dealing with an uncooperative furnace right now or are just looking to avoid future problems, read on for useful advice on how to recognize and fix 9 common furnace issues.

Determining whether it’s a problem with your furnace or your home’s ventilation system

For many people, the first sign of a furnace problem is extreme discomfort indoors. If your furnace is the cause of your cold, drafty house, you’ll need to examine your home’s insulation and airflow to determine the best course of action. If you notice that your furnace isn’t providing enough heat to keep up with your house’s demands, it’s possible that there isn’t enough insulation in your walls and ceilings. In this case, it’s best to call in an expert to conduct an insulation audit and recommend a course of action. Furnaces also need to be vented outside the house to operate safely and efficiently. If your furnace vents are blocked or disconnected, it will struggle to distribute heat throughout your home. A good way to test this is to go outside and listen for a whooshing or gurgling sound coming from your furnace.

A musty smell from your furnace

If your furnace smells musty or mildew, you might have a problem with your humidifier. The humidifier is a device that helps regulate indoor humidity levels and is often found in areas with low natural humidity in the air. However, if your humidifier is clogged with debris or if the water tray is empty, the device won’t be able to perform its function. If the humidifier is full of debris, this could cause bacteria and mold to grow inside your furnace and circulate through the rest of your house. A musty smell coming from your furnace might not be a problem with the furnace itself, but rather a result of water and mold growing inside your furnace.

Noisy operation of your furnace

If you notice that your furnace is making strange grinding, clanking, or squealing noises, it’s likely that something has become lodged in the moving parts inside. To troubleshoot this potential problem, unplug the furnace and then carefully inspect the interior for any obstructions. If you find something caught in the furnace’s moving parts, carefully remove it and then plug the furnace back in. If the strange noises don’t cease after cleaning the furnace, it’s probably time to call a professional to perform a thorough inspection of the unit.

The erratic temperature inside your home

If you’re experiencing extreme hot and cold temperatures inside your home with no discernible pattern, it may be time to check your thermostat. First, check the thermostat’s settings to make sure that it’s set at the right temperature. A common cause of temperature inconsistency is misreading the thermostat’s settings due to dust or other debris on the thermostat’s display. If your thermostat is fine, check your furnace to ensure that it’s operating normally. It could be that your furnace isn’t able to meet your home’s current temperature needs. If you have a gas furnace, a blocked or disconnected vent could also be causing your home to overheat. If you have an electric furnace, you may need to install a manual reset circuit breaker. In some cases, a furnace’s inability to meet your home’s temperature needs could be a sign of a larger problem, like a faulty wiring or control board. In this case, it’s best to call a professional to diagnose the source of the problem.

Lack of heat from your furnace

If you notice that your furnace isn’t turning on at all, the first thing you’ll want to check is that it’s receiving power. Assuming that it is, the problem could be as simple as a faulty breaker switch or thermostat. If the switch and thermostat are both operating as intended and your furnace still isn’t kicking on, it might have tripped a circuit breaker. This can happen if your furnace has been operating for an extended period without stopping to cool down. If your furnace is tripping the circuit breaker repeatedly for no reason, it could be because the furnace is too large for your electrical panel. In this case, you’ll need to contact an electrician for assistance. If your furnace turns on but doesn’t produce any heat, it could be clogged with debris or have low voltage. If the latter is the case, you may need to get your furnace serviced. A faulty wiring or control board could also be the cause of your furnace’s lack of heat. In this case, it’s best to call a professional to diagnose the source of the problem.

Blowing cold air from the vents

If you’ve recently turned on your furnace and notice that it’s blowing cold air, it’s probably because your furnace isn’t receiving power. Once you plug the furnace back in, it will take some time for it to heat up. This means that at first, you may feel cold air coming from the vents. However, once the furnace has time to heat up, it should produce warm air again. If you’ve recently turned on your furnace and are still blowing cold air, you may need to clean your furnace filter. A dirty or clogged filter can cause your furnace to work harder and will often result in blowing cold air. To clean your filter, unplug your furnace and then locate the filter in the furnace’s air intake. After removing the filter, you can either wash it with soap and water or replace it with a new filter.


If you’ve read this article from start to finish, you’re now well-equipped to deal with any furnace issues that may arise. From making sure that your filters and vents are clean to knowing how to deal with extreme temperatures inside your home, this article has provided you with all the information you need to keep your furnace in tip-top shape. So don’t let your furnace give you a hard time—follow these tips and take care of your furnace before it’s too late! Not all furnace problems are created equal. Some may be easy to fix while others will require the services of a professional. Armed with this knowledge, you’ll be able to identify and troubleshoot the 9 most common furnace issues and make the most of your furnace’s full potential.