There’s no doubt that Lincoln winters can get extremely cold. Having a reliable heating system is an absolute must to get your family safely through the winter. Unfortunately, all heating systems will experience malfunctions from time to time. One of the most frustrating ones you may experience is your furnace blowing cold air. Below, we’ll look at some of the most common reasons this can happen so you can successfully troubleshoot and repair your unit as quickly as possible.
A Look at Standard Furnace Operation
Before we dive into what may be wrong with your furnace, it’s important first to understand its normal operation. When your thermostat senses that the temperature in your home is below your desired setting, it signals your furnace to turn on. The furnace ignites its burner or heating element, depending on the type of energy that it uses.
Furnaces can run on natural gas, propane, heating oil, or electricity. The heat exchanger warms up, and the blower fan turns on. This pushes warm air throughout your ducting to the various rooms in your home. Whenever your thermostat senses the temperature has reached your desired setting, it will signal the system to shut off.
Brief Chill of Startup Mode
One reason that your furnace may be blowing cold air is that it’s simply part of its startup routine. This is especially common with high-efficiency furnaces that use advanced controls to protect their internal components. When your furnace first starts up, the blower fan will kick on before the heat exchanger gets warm enough to heat the air.
This leads to a one- to two-minute lapse where lukewarm air gets circulated through your home before it starts to warm. If you notice that your furnace is only blowing what seems like cold air for a couple of minutes before it turns warm, it’s part of its normal operation, and there’s nothing you can really do about it.
Wrong Blower Fan Setting
If you take a look at your thermostat, it has settings for the blower fan. This is the fan that circulates air throughout your ductwork. You can set the fan to off, on, or auto. It’s very common for homeowners to set their blower fan to on without realizing exactly what they’re doing.
When you set your blower fan to on, it will run nonstop. This means that it will circulate hot air when your heating system is running. However, it will circulate room-temperature air whenever your heating system turns off. Instead of having your blower fan set to on, you want to set it to auto. This ensures that your blower fan only turns on whenever your heating system kicks on.
Clogged Air Filter
Your furnace has an integrated air filter that’s responsible for trapping airborne contaminants before they reach the inside of your furnace. Over time, as the filter traps more and more debris, it will become clogged. If you don’t change the filter when it’s clogged, it can restrict the airflow through your ducting.
If your furnace isn’t able to push the hot air it produces through the air filter, it’s going to feel like the air isn’t very warm. Unfortunately, your furnace will likely shut down as a safety mechanism due to overheating of its components, since the hot air isn’t circulating.
When your furnace shuts down, your blower fan can continue to run throughout the cycle and circulate room-temperature air that feels cold throughout your home. Fortunately, this is a straightforward fix. All you have to do is replace the air filter for your system. We recommend checking the air filter monthly and replacing it as needed.
Ignition Malfunction
If your furnace relies on natural gas, propane, or heating oil to create heat, it needs a burner to ignite that fuel. Older furnaces rely on a standing pilot light flame, while newer furnaces rely on an electric igniter that sends a spark to the burner. If either of these fails, your furnace’s burner won’t light, making it unable to generate heat.
Unfortunately, your blower fan will likely still run as your furnace repeatedly tries to start, which can circulate cold air throughout your home. There could be several reasons why you’re having ignition problems with your furnace. Some of the most common include a dirty pilot assembly, a faulty flame sensor, and gas supply issues. It’s important to have one of our technicians thoroughly assess your unit and remedy the problem to restore functionality to your heating system.
Cracked Heat Exchanger
Your furnace’s heat exchanger is responsible for transferring heat from the hot exhaust fumes to the air that circulates throughout your ducting. If this heat exchanger becomes cracked, damaged, or excessively dirty, it can affect heat transfer. Sometimes, a heat exchanger issue can cause the burners to shut off as a safety mechanism.
This will allow cold air to circulate throughout your home as your furnace isn’t running. If you suspect a heat exchanger issue, it’s a good idea to have one of our professionals further assess your unit. This situation can be pretty dangerous, as it can allow toxic fumes to seep into your home. In many cases of a cracked heat exchanger, it’s more cost-effective to replace your unit than try to repair the heat exchanger component.
Electrical Malfunction
Another culprit behind why your furnace may be blowing cold air is an electrical malfunction. If you take a look at any modern furnace, you’ll see many different control boards and sensors that work together to manage your heating cycle.
Unfortunately, all it takes is a failure of one of these electrical components to cause problems for your entire system. Electrical issues can cause burners to shut off unexpectedly, the blower fan to run continuously, and inconsistent heating output. It’s important to have one of our professionals further assess the control board and electrical issues with your unit, as both require a proper diagnosis.
Ducting Issues
Sometimes, the cold air issue may not actually be a problem with your furnace. It could be an issue with your ductwork. Your furnace could be producing warm air that never reaches your living space. If you have leaky or poorly insulated ductwork, air can easily escape into wall and floor crevices instead of making it to the rooms in your home.
By the time the air travels to your rooms, it can feel slightly cooler or lukewarm. This issue is prevalent in homes with ducting that’s over 10 years old. To remedy this issue, you’ll need to invest in duct cleaning and sealing services to eliminate these unwanted air leaks.
Reliable Furnace Repair Service
John Henry's Plumbing, Heating, Air, and Electrical offers reliable furnace repair service for the Lincoln, NE community. We can also assist with all your furnace installation, replacement, and tune-up needs. Reach out to our office today to schedule an appointment with one of our helpful heating technicians.
