You turn to your furnace for warmth and comfort during the colder days of the year. But what happens when you switch on your heating system only to find that it’s blasting cold air instead of hot?

A furnace releasing cool air into your home may seem worse than having no heat at all. However, if you’re nervously looking for answers to “Why is my furnace blowing cold air?” on the web, there’s no reason to panic. We’ll review common reasons why this problem occurs. Once you know how to troubleshoot a furnace blowing cold air, you can fix the problem in no time.

Your Thermostat is on the Wrong Setting

Are you wondering why the furnace is blowing cold air all of sudden? If so, first turn to your thermostat. 

When your furnace’s blower fan is switched from “AUTO” to “ON,” the fan runs continuously, whether your furnace is generating warm air or not. Changing the thermostat setting back to “AUTO” will guarantee that the fan only blows when intended, stopping any unwanted cold air from circulating.

This is one of the most simple fixes for how to troubleshoot a furnace blowing cold air. However, checking your fan settings may not have fixed the problem, which is where the following three tips come in.

Your Furnace Filter Is Dirty

The furnace air filter in your home eliminates the dirt and debris that collects over time. This filter must be changed or replaced routinely to ensure no clogs form.

Dirty air filters restrict the airflow to your furnace’s heat exchanger, which can lead to overheating issues. As a result, your furnace’s high limit switch may be tripped, signaling the burners to turn off to prevent the heat exchanger from cracking. When your heating system shuts off, it may feel like the furnace is blowing cold air into your home.

The Condensate Line Is Blocked

Much like with a filter, dust and debris can create blockages in your furnace’s condensate line. If you have a high-efficiency furnace and notice water collecting around the base of your furnace, the condensate line may be clogged.

Since high-efficiency furnaces create condensation (or moisture) as they operate, condensate lines transport this condensation away from the furnace. However, water can back up into your furnace if the line is clogged. An overflow kill switch will turn off your furnace as a preventative measure when this happens.

The 4 Steps to Clear Condensate Drain Line Blockages:

  1. Cut the power to your furnace at the breaker. Safety first!
  2. Find and remove water in the condensate drain pan (using a wet/dry vacuum).
  3. Clean the pan with a simple water and dish soap mixture.
  4. Use the wet/dry vacuum to remove clogs at the condensate drain pipe.
  5. Switch your furnace back on.

The Pilot Light Is No Longer Lit

We’ve gone over three common problems for how to troubleshoot a furnace blowing cold air. But after checking all of the above, you may still be asking why the furnace is blowing cold air if you haven’t the right solution yet. In that case, an extinguished pilot light could be to blame.

Older gas furnaces have standing pilot lights that produce a blue flame. Furnace pilot lights can go out for several reasons, from a thermocouple malfunction to a sudden gust of air.

Fortunately, it’s possible to relight a furnace pilot light yourself. Nonetheless, if you are unsuccessful at relighting the pilot light, don’t hesitate to seek professional furnace repair in Greenville, SC. The problem could have to do with your gas valve, which requires expert attention.

You Have Leaking Air Ducts

It’s also possible that your furnace’s hot air is leaking out through holes in your air ducts.

Leaks and disconnections in your air ducts often occur due to old age. It’s vital to have a professional HVAC technician inspect your air ducts and perform the necessary repairs.

We’re Here to Help

We’ve gone over many common problems to help you better troubleshoot a furnace blowing cold air. Hopefully, your furnace will be back to heating the air quickly. However, if you’re still wondering why the furnace is blowing cold air, calling an experienced technician for heating repair in Greenville, SC, may be the best solution. 

The Absolute Climate Control team is here to help get your furnace back into working order so you can heat your home properly. Contact us today to schedule a heating system repair!

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