Troubleshooting a Furnace That Blows Cold Air
Few things can seem more frustrating than your furnace not blowing hot air during the frigid winter months. Unfortunately, it can happen from time to time due to various issues. Below, we’ll address how to troubleshoot this problem on your own and when to contact our experienced technicians for professional assistance.
Dirty Air Filter
One of the most common culprits behind a furnace that seems to be blowing cold air is a dirty air filter. When the filter clogs with debris, it restricts airflow through your ducting. When your system can’t pull in enough air, it can overheat and shut down due to its built-in safety mechanisms. This can leave the blower fan running even when your furnace isn’t running. Fortunately, this is a straightforward fix. All you need to do is remove the dirty air filter and replace it with a new one. Make sure your new air filter is the same size as the old one so that the furnace will work correctly.
Wrong Blower Fan Setting
If you take a look at your thermostat, you will see three different settings for the blower fan: Off, On, and Auto. Whenever your blower fan is set to Auto, it turns on whenever your furnace kicks on. This ensures that hot air circulates only when your furnace is running. Unfortunately, if you set your blower fan to On instead, the blower fan will run nonstop.
This means it won’t turn off when your furnace turns off. Rather, your blower fan will still be circulating air that will likely feel cooler when it comes out of your vents. This is another easy fix, as all you have to do is change your blower fan’s thermostat setting to Auto.
Ignition Errors
When your thermostat signals to your furnace that it’s time to turn on, it turns on both your furnace and the blower fan. Any furnace that burns natural gas, heating oil, or propane to produce heat needs an active burner flame. On older furnaces, there’s a pilot light that ignites the burner. On newer furnaces, there’s an electric igniter that sends a spark to ignite the burner. If either the pilot light or the electric igniter fails, the burner won’t light.
The blower fan will still be running and circulating unheated air, though. If you look at your furnace and don’t see a flame on the burner, it’s time to contact one of our furnace technicians to take a closer look. We may need to replace the electric ignitor or flame sensor. Or we may be able to clean the flame sensor photo eye to get your furnace working again.
Overheated Furnace
All modern furnaces come with a built-in safety feature that shuts the furnace down when it senses that it’s overheating. This is necessary to prevent an electrical fire in your home. However, it’s crucial to realize that your blower fan may still run even though your furnace has shut down due to overheating.
Your furnace could overheat for several reasons. Some of the most common include a dirty air filter, blocked air vents, blower motor problems, and dirty internal components. If you’ve checked your air filter, and it seems fine, check the exhaust vent on your furnace to see if anything is blocking it. If not, it’s best to ask a professional technician to assess the issue further.
Faulty Limit Switch
Your furnace has a limit switch that tells the blower motor when to turn on and off based on how your furnace is functioning. When that limit switch malfunctions, it can leave the blower fan running even though your furnace isn’t. If you suspect a faulty limit switch, one of our technicians can perform thorough testing to confirm that this is the issue. Sometimes we can replace a faulty switch, while at other times we may need to repair the wiring going to it.
Top-Notch Heating Repair Services
Our HVAC and plumbing company offers top-notch heating repair services for the Paxton, IL community. We can also help with all your heating installation, maintenance, and replacement needs.
Call our team at Dogtown Heating, Air & Plumbing today to book your service appointment with one of our helpful heating technicians.
