Here in Minnesota, we know the signs of winter all too well. The temperature is dropping. Days are getting shorter, nights are getting longer. And it’s time to turn on the Furnace to keep our homes warm and cozy. 

One problem that we see often is a furnace that turns on but only blows out cold air. This can be surprising and frustrating for our customers.

Here are 10 common reasons why you may notice cold air coming from the furnace. Some of them are simple fixes while others may require the attention of an HVAC professional.

1. The thermostat isn’t set properly. It may have been a while since you set the thermostat, or it may have been changed accidentally. Check that the thermostat display is on, the batteries are charged, the fan is set to “Auto,” and the set temperature is what you intend. If the fan is set to “On,” the furnace will keep running even if heat is not needed.
2. Dirty air filter – At the beginning of the heating season, it’s easy to forget to replace the old air filter with a new one. When the air filter is covered in dust, dirt, pet hair, or other particles, the airflow is disrupted. This diminishes the performance of your furnace.
3. The pilot light is off – While newer furnaces often have an automatic pilot light for heating, older units may have a pilot light that needs to be restarted manually.
4. Faulty electronic ignition. Even newer furnaces can have issues starting. Sometimes the electronic ignition just needs to be adjusted while other times it needs to be replaced.
5. Faulty gas valve – Over time, dirt and debris can build up on the gas valve, which causes it to stick. Without the flow of natural gas, the pilot light won’t ignite and the furnace can’t create heat. A furnace cleaning from an HVAC professional should fix this problem.
6. Faulty thermocouple – The thermocouple is a sensor that controls the gas valve and ignition. If there’s a problem with this small part, the pilot light can extinguish repeatedly. Have an HVAC professional adjust or replace it.
7. Faulty flame sensor – If the flame sensor is dirty, the furnace will start blowing hot air but then the burner will shut off, which will result in cold air. Have an HVAC technician inspect and clean the sensor to see if that solves the problem.
8. Dirty burner – Finally, if the burner itself is covered in dirt or other grime, then it will have a hard time lighting and won’t be able to heat the air like it’s supposed to.
9. Your furnace hasn’t warmed up – If you’re turning on your furnace for the first time since the cold weather has come, the furnace may take some time to warm up. Give it a few minutes and monitor the air coming out of the vents. If you’re still having trouble with cold air coming from your furnace, contact DeZiel HVAC for professional diagnosis and repair. We can help you get your home warm and comfortable in the shortest possible time.
10. Your furnace may have overheated – Your furnace has a safety mechanism that will turn off the furnace if it overheats. If you think that could be the issue, shut down your furnace and let it cool for a few minutes before restarting it. It’s important to find out why it has overheated and address that issue. Common causes are a dirty air filter, mechanical failure, and age.

How to Prevent Your Furnace Blowing Cold Air

They say prevention is the best medicine and that adage applies to home heating systems too. To ensure your furnace is running optimally, there are some preventive maintenance steps you can take:

1. Change Your Furnace Filter: A dirty furnace filter can restrict air flow, causing your furnace to blow cold air. Inspect and change your furnace filter every month or two during the heating season.
2. Test Your Thermostat: An inaccurate thermostat setting causes the furnace to run longer than it should and may result in the furnace blowing cold air. Test your thermostat and adjust the settings as needed to ensure that it’s working properly.
3. Check Your Ductwork: If you have leaks in your ductwork, this can cause the heated air to escape before reaching its intended destination. Inspect your ducts for any holes or tears, and repair any that you find.
4. Clean Your Coils: Dirt and other debris can accumulate on the coils, causing them to overheat too quickly and shut off before your desired temperature is reached. Clean the inside of your furnace regularly (including all internal parts) to ensure proper airflow and prevent dirty coils from affecting system performance.
5. Schedule Yearly Maintenance: Have a professional inspect and service your furnace at least once a year. An experienced technician can identify any potential problems and make necessary repairs before they cause major issues.

By taking these steps, you can help prevent your furnace from blowing cold air and keep it running efficiently all season long.

DeZiel HVAC Can Help You Get to The Bottom of Your Furnace Problem

As you can see, many of these issues can be prevented or resolved with regular maintenance and cleaning of your furnace. We have a long winter ahead of us – so don’t put up with cold air coming out of your heating system now. Call DeZiel Heating & AC at 763-684-3965 for expert diagnostics and repair service.

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