Why is My Furnace Blowing Cold Air? Troubleshooting Tips from AV Heating & Cooling

A furnace blowing cold air can be frustrating, especially when the temperatures drop. While it might seem like a major issue, there are a few troubleshooting steps you can take before calling in a professional.

AV Heating & Cooling has been the trusted HVAC expert in Independence and surrounding areas since 2009, and we’re here to help you identify some common causes of this issue.

In this blog, we’ll guide you through practical steps to restore your furnace’s performance and keep your home warm and cozy.

Here are the 9 most common reasons your furnace is blowing cold air.

 

1. Thermostat Issues
   The first most common cause of your furnace blowing cold air is your thermostat. Since your thermostat controls your home’s temperature, incorrect configuration can lead to cold air coming through your vents. You’ll want to verify the settings and your thermostat to make sure that someone hasn’t changed them. You want to ensure the thermostat is set to ‘heat’ and not ‘cool, make sure the fan is set to ‘auto’, and make the temperature is set where you would like it.

   A furnace with dead or dying batteries, can also cause the thermostat to malfunction, so changing your batteries may be helpful as well. If any of these settings are incorrect, make the appropriate changes and your furnace should begin blowing warm air. Keep it mind it takes about 15 minutes for a furnace to heat up, so please be patient and allow it time to warm up.

   

2. Dirty Air Filter
   If your furnace is still blowing cold air, the next place to check is your air filter. Your air filter traps dirt, dust, and debris within your system and if not changed routinely can lead to restricted airflow in your system. When the airflow is restricted, the cold air entering the furnace from the return ducts is limited and leads to your furnace not having sufficient air to heat.

   Further, a dirty air filter and cause your furnace to overheat and go into safety mode. Depending on household factors like pets and allergies, it’s recommended that your furnace filter be changed every 30 to 90 days. If it’s been a while, putting in a fresh air filter just might do the trick.

   

3. High Limit Switch Issues
   If your furnace filter was dirty and replacing it didn’t help, the issue may be a faulty high limit switch. This switch measures the temperature of the air that passes over the heat exchanger within your system and shuts down the furnace if it overheats. Lack of airflow is a very typical cause of your furnace overheating. If you experience frequent tripping of the high limit switch, it can cause the switch to fail. If your blower continues to run between cycles or cycles on and off, this typically indicates a faulty limit switch. Give the professionals at AV Heating & Cooling a call at (816)796-0300; we’d be happy to get this issue taken care of for you.

   

4. Fuel Issues
   A lack of fuel can be another common cause of a furnace blowing cold air. Based on your type of furnace, it runs on either electricity or fuel.
   1. If you have an electric furnace, it won’t function without electricity. You will want to ensure that the switch in your utility room that powers your furnace is in the ‘on’ position. You will also want to check at your breaker box and make sure that the breaker is in the ‘on’ position and has not tripped.
   2. If you have a gas furnace, it won’t heat up if the gas supply has been shut off, the gas valve has been turned off or has seized, or if the propane/oil tank is empty. You will want to check to make sure there are no issues with your gas supply and that the appropriate gas valve is open

   

5. Clogged Condensate Line
   Another common cause of your furnace blowing cold air is a clogged condensate line. Condensation from your furnace drains away via the condensate line, which is a white PVC pipe that runs down the furnace’s outside and empties into a floor drain.

   If the pipe becomes clogged, the condensation will accumulate in the drip pan and trigger the float switch. The float switch is a safety feature that shuts down the furnace when the condensation doesn’t properly drain to prevent water from spilling over the drip pan.

   If you find a clogged condensate line is your issue, the clog must be cleared for your furnace to function properly. As a homeowner, you can try to take on this maintenance task, but the professionals at AV Heating & Cooling have specialized tools to make the job easier and more efficient – https://avheatingandcooling.com/contact-us/

1. 1. Before trying to clear the clog, you will want to make sure you turn off the power to your furnace. You can do this by flipping the switch (resembles a light switch) on the furnace or by turning off the breaker for your furnace at your circuit breaker.
   2. Inspect the end of the condensate white PVC pipe for debris. If you find any, they can be removed with a brush or a small screwdriver.
   3. If you didn’t find any clogs at the end of the pipe, you can remove the cap near the top of the pipe and flush the line with a solution of equal parts white vinegar and hot water. You can repeat this process several times if needed.
   4. Once you have cleared the clog, restore power to your furnace and give it time to warm up.

6. Ductwork Issues
   Leaking or incorrectly sized ductwork can also lead to issues with your furnace blowing cold air. Call in the experts at AV Heating & Cooling to properly check and repair your ductwork to ensure optimal heating performance of your furnace.
   1. If your ductwork is leaking, it can cause warm air to leak out as well as allow cold air to enter through the openings in the ducts. Leaks are caused when ducts become disconnected or cracked.
   2. If your ductwork is incorrectly sized, it can cause issues with the heating performance of your system. If your return ductwork is too small, it won’t be able to handle the volume of air that’s needed to properly heat your home. This will need to reduced airflow through the system and will cause your furnace to blow cold air. Ductwork that is too big causes the air pressure to significantly decrease and therefore the airflow doesn’t make it to all the parts of your home.

   

7. Flame Sensor Issues
   A dirty or malfunctioning flame sensor can be another common cause for your furnace blowing cold air. The flame sensor is a safety device that will turn off the gas supply to the burners in your furnace if they don’t ignite. These sensors can become coated with dirt, soot, or other carbon deposits and make them incapable of sensing the flame.

   You can access and try to clean off the flame sensor or call in the professionals at AV if you don’t feel comfortable or if you think the sensor needs replaced. Call us anytime at (816)796-0300.

   First, make sure you turn off the gas to the furnace and then remove the front panel where you will find the ignitor or ignition sensor near the burners. If the sensor or ignitor is dirty, you can remove it carefully with a screwdriver and gently clean it – be careful not to break it. Once cleaned, replace it back how you found it, put the front panel back on, turn on the gas, and then turn your furnace on.

8. Electric Ignition / Pilot Light Issues
   A faulty electric ignition or an issue with your pilot light can also cause your furnace to blow cold air. If your furnace was manufactured prior to 2010, they generally were still using pilot lights. More modern furnaces will use an electronic ignition.
   1. If your furnace has a pilot light, check to see if the flame has been blown out by a strong draft. If the flame has blown out, you will want to consult your furnace’s manual for instructions on re-lighting the pilot light. If the flame continues to go out, there may be dust or debris built up on the pilot light causing a bad connection.
   2. If you have a more modern furnace with an electric ignition, these electronic ignitions can fail and would require a call to the professionals at AV Heating & Cooling at (816)796-0300.

   

9. Incorrectly Sized Furnace
   Another common cause of a furnace blowing cold air is an incorrectly sized furnace for the home. Size matters when it comes to your furnace system. If you’ve recently installed a new furnace and find yourself puzzled by its failure to product hot air, chances are it’s undersized for your home. An improperly sized furnace can result in the circulation of cold air and can lead to issues with both effectiveness and efficiency.

   When your furnace is too small for your home, it struggles to accurately gauge the internal temperature, often resulting in the distribution of cool air. Conversely, an oversized furnace may cycle on and off unexpectedly, causing disruption to your comfort and potentially leading to higher energy bills.

   Our HVAC professionals are expertly trained to help your select the right size furnace for your house and your individual comfort needs. You can request an appointment anytime – https://avheatingandcooling.com/contact-us/

There are a handful of more serious issues that could be causing your furnace to blow cold air and would require a call to the professionals at AV. Our technicians are expertly trained to diagnose and resolve these issues and have you back up and running quickly! Call now at (816)796-0300!

• Malfunctioning Gas Valves
• Cracked Heat Exchanger
• Blocked Burner
• Clogged Coil
• Faulty Circuit Control Board

Opting for professional furnace maintenance with our AV Maintenance Plan through AV Heating & Cooling is a proactive step towards safeguarded your home comfort. Our skilled technicians offer a comprehensive inspection of your heating system, proactively identifying potential issues before they lead to your furnace blowing cold air. By addressing these concerns, our team not only boosts your furnace’s efficiency but also guarantees its safe and dependable performance.

Our trained experts can pinpoint and resolve underlying issues that might escape the untrained eye, preventing unforeseen breakdowns and sparing you from expensive repairs down the line. With AV’s Maintenance Plan, you can rest assured that your furnace is in optimal condition, ready to keep you warm and cozy all season long. Learn more here – https://avheatingandcooling.com/av-maintenance/

If your furnace is still blowing cold air after trying these troubleshooting steps, it’s time to bring in the experts. At AV Heating & Cooling, we’ve been serving Independence and surrounding areas since 2009, providing trusted HVAC solutions to keep homes comfortable year-round.

Our team is ready to diagnose and resolve your furnace issues quickly and efficiently. Contact us today at (816)796-0300 to schedule an appointment and let us get your furnace back to delivering the warmth you need!