Brr! Why Is My Furnace Blowing Cold Air? - PGA Inc.


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Brr! Why Is My Furnace Blowing Cold Air?

You might have alarm bells going off if you notice the furnace blowing cold air all of a sudden. One minute, you’re cozy, and the next, you’re shivering while trying to get in contact with a heating repair service in Wausau, WI. Fortunately, there’s no need to panic! There are multiple reasons why your heating system might suddenly start blowing cold air instead of warm air. Explore the common causes of a furnace blowing cold and what you can do to restore comfort in your home.

Common Reasons for a Furnace Blowing Cold Air

From simple oversights to more complex mechanical failures, let’s delve into the most common reasons for a furnace blowing cold air. Understanding these causes will not only help you identify potential issues quickly but also guide you in taking the right steps to restore your furnace’s proper heating function. Whether it’s a dirty air filter affecting airflow or a more intricate problem with the pilot light or heat exchanger, we’ve got you covered with detailed insights.

1. Thermostat Settings

The first thing to check when your furnace is blowing cold air is the thermostat. Incorrect thermostat settings can cause the furnace to blow cool air. Ensure it’s set to “heat” and not “cool,” and check that the fan setting is on “auto” and not “on,” which can cause the fan to run continuously, blowing cold air even when the furnace isn’t heating.

2. Pilot Light and Flame Sensor Issues

In gas furnaces, the pilot light is a small flame that ignites the main burner. A furnace will blow cold air if the pilot light goes out or if the flame sensor is dirty. The flame sensor monitors whether the pilot is lit. If it’s malfunctioning or dirty, it might fail to detect the flame, causing the furnace to blow cold air instead of hot air.

3. Dirty Air Filter

A dirty air filter can restrict airflow, causing the furnace to overheat and blow cold air. Regularly checking and replacing your air filter can prevent this issue and ensure efficient operation.  

4. Gas Supply Problems

Issues with the gas supply can affect the furnace’s ability to produce warm air. If there’s not enough gas reaching the furnace, it may start to blow cold air. Check if the gas valve is fully open and ensure there’s no issue with your home’s gas supply line.

5. Overheating

If the furnace overheats, it may start to blow cold air to cool down. Overheating can be caused by a clogged furnace filter, restricted airflow, or mechanical issues. It’s important to address overheating quickly to avoid damage to your furnace.

The high limit switch prevents the furnace from overheating. If it’s faulty or incorrectly set, it can cause the furnace to blow cold air to prevent overheating.

6. Electric Furnace Issues

An electric furnace may blow cold air due to issues like a tripped circuit breaker or problems with the heating elements. The furnace control board manages the operation of the furnace. If it’s malfunctioning, it might cause the furnace to blow cold air. A professional HVAC technician should inspect the control board to ensure that your electric furnace is receiving power and that all electrical connections are secure.

7. Heat Exchanger Issues

A problem with the furnace’s heat exchanger can cause it to blow cold air. A cracked heat exchanger is a serious issue that can lead to inefficient heating and even pose a safety risk.

8. Ductwork Issues

Leaking or poorly insulated air ducts can lead to cold air blowing through your heating system. Inspect your ductwork for leaks or damage that might be causing heat loss.

Keep Your Furnace in Good Shape With Maintenance and Prevention

Changing your air filter regularly is one of the easiest ways to prevent a furnace from blowing cold air. A clogged air filter can cause multiple issues, including restricting heated air flow. We recommend changing the air filter every 30 days. One of our qualified HVAC technicians can help replace your air filter when performing an annual inspection of your furnace. This can identify potential problems before they cause your furnace to blow cold air.

For gas furnaces, regularly check the pilot light and the pilot light assembly. If the pilot light frequently goes out, it may need adjustment or cleaning. Also, ensure that your furnace has a consistent and adequate gas supply. Issues with the gas supply line can lead to insufficient heating.

And finally, pay attention to the heating cycle of your furnace. Irregular or short cycles can indicate a problem that might lead to cold air blowing.

When to Call a Professional

Some furnace issues require professional diagnosis and repair. An experienced HVAC technician can solve complex problems that cause a furnace to blow cold air by performing advanced diagnostics — this can include checking the furnace control board, flame sensors, heat exchanger, and even the condensate drain lines for blockages.

It’s also safer to trust repairs to an HVAC professional. Working on gas furnaces involves risks, especially when dealing with the pilot light, gas valve, or gas supply. Don’t take needless risks with these dangerous components if you don’t have to. 

Stay Warm Through the Winter With PGA Inc.

A furnace blowing cold air can be caused by a variety of issues, ranging from simple fixes like changing a dirty air filter to more complex problems like a malfunctioning heat exchanger. Regular maintenance and timely intervention by a qualified HVAC technician are key to ensuring your furnace efficiently provides warm air throughout the heating season. 

When you need a helping hand, turn to Wausua’s best heating technicians at PGA Inc. We have experience with all furnace makes and models, so you know we’ll take good care of your heating system. Contact us today to restore comfort to your home!

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