5 Common Furnace Problems and How to Troubleshoot Them

Furnaces are essential for keeping your home warm and comfortable during the colder months. However, like any other home appliance, furnaces can experience problems that can disrupt their functionality. From strange noises to inconsistent heating, these issues cause inconvenience and could lead to a costly furnace repair in Barrie if left unaddressed. To help you troubleshoot your furnace problems, here’s a list of the five most common issues and their possible solutions:

Furnace Problems

1. Dirty Filters

One of the most common furnace problems is dirty filters. When filters become clogged, they restrict airflow, causing your furnace to work harder and longer, which may result in higher energy bills. A dirty filter can also lead to poor indoor air quality and reduce the lifespan of your furnace.

How to troubleshoot: To avoid this problem, you should clean or replace your furnace filters every one to three months. To clean your filter, remove it from the furnace and use a soft brush to remove the dirt and debris. If you have disposable filters, replace them with new ones.

2. Pilot Light Issues

The furnace’s pilot light creates the flame that heats the air flowing through the furnace. If the pilot light is out or not working correctly, your furnace won’t start, leaving you cold.

How to troubleshoot: To fix this problem, first, turn off your furnace. Then, check if the pilot light is on; if it’s off, follow the manufacturer’s instructions to relight it. If the pilot light keeps going out, there may be a problem with the thermocouple, and it’s recommended that you consult an HVAC professional.

3. Faulty Thermostat

A faulty thermostat can cause your furnace to turn on and off frequently, leading to inefficiency, higher energy bills, and uneven heating. It can also cause the furnace not to start at all.

How to troubleshoot: Before calling an HVAC professional, check if the thermostat is set to the right temperature. Then, inspect the wiring for any loose connections or damages. If you’re still having issues, it’s time to call an HVAC professional.

4. No Heat

One of the most alarming furnace problems is having no heat. It could be due to various reasons, such as a clogged air filter, a malfunctioning blower fan, or a faulty limit switch.

How to troubleshoot: First, check the air filter and ensure it’s not clogged. Then, check if the fan is functioning correctly by turning on the furnace and observing if the fan is blowing warm air. If the furnace is blowing cold air, it might be a limit switch problem, and it’s recommended that you call an HVAC professional.

5. Unusual Noises

Furnaces make some noise when they’re running. However, loud or unusual noises such as banging, squealing, or rattling can indicate potential problems such as loose parts, wear and tear, or dirty burners.

How to troubleshoot: Don’t ignore loud or unusual sounds from your furnace. First, turn off your furnace and inspect the interior for loose or damaged parts. If you cannot locate or fix the problem, call an HVAC professional for further inspection.


In conclusion, keeping your furnace in good working order is essential for staying cozy and warm during winter. By familiarizing yourself with these five common furnace problems and how to troubleshoot them, you can save money, avoid unexpected furnace breakdowns, and create a safe and comfortable environment for your home. However, suppose you’re unsure of how to troubleshoot any furnace problems. In that case, it’s always best to call a trusted HVAC professional to diagnose and fix the issue.