4 Possible Reasons Why Your Heating System Is Blowing Cold Air

Even though the winters in Texas are usually quite mild, there are still plenty of days each year when you’ll need your heating system to help you stay warm. Having cold air blowing out of your vents when your heating is on can be incredibly frustrating, and there are a few different reasons that it can happen. Let’s take a look at the most common issues that can cause a heating system to blow cold air and what you can do about them.

1. Incorrect Thermostat Settings

If your heating system ever blows cold air, the very first thing to check is that your thermostat is set correctly and on heating mode. You’ll also want to make sure that the fan is set to “Auto” and not “On.” The “Auto” setting means that the fan will only ever operate when the furnace or heat pump is running, while the “On” setting will leave the fan running constantly. Not only will leaving the fan set to “On” lead to increased energy costs, but it will also cause your heating system to start blowing cold air.

Whenever the fan runs, it draws in cold air from the return-air vents. In a heat pump system, the cold air is forced over a coil filled with hot refrigerant. If you have a furnace, the cold air is forced over the unit’s heat exchanger. In either case, the heat raises the temperature of the air, and the hot air is then blown through the supply ducts and out all the vents.

If the fan continues to run when the furnace or heat pump is shut off, it will quickly result in cold air blowing out of your vents instead. This issue can easily be avoided by always leaving the fan set to “Auto.”

2. Ductwork Issues

Leaky or damaged ductwork can sometimes also cause a heating system to blow cold air, and the same is true if you have any ductwork in the attic or crawlspace that isn’t fully insulated. Any gaps or holes in the ductwork will allow lots of hot air to escape and it can also let cold air inside. As a result, the air coming out of the ducts will be far cooler than it was when it first left the furnace or air handler.

All ductwork that runs through unconditioned areas like a crawlspace should be fully wrapped with insulation. If the ducts aren’t well insulated, all of the cold air surrounding them can penetrate through the sheet metal and quickly cool off the air inside the duct system. This can again result in the heating system blowing cold air out of the vents in some rooms.

3. Dirty Furnace Burners

This issue only occurs with gas furnaces, and it can easily be avoided by having your heating system professionally maintained every fall. As the furnace runs, its burners eventually start to be covered with grime, and this can prevent them from burning gas properly. Dirty furnace burners often lead to incomplete combustion, which is when the gas inside the unit doesn’t burn entirely. This results in the furnace producing far less heat and can cause cold air to start blowing out of those vents that are at the farthest ends of the duct system.

This is an issue that you can easily check for on your own by looking inside the furnace to see the color and condition of the flames. When working correctly, all the burners should produce a strong, steady orange flame. If any of the flames are weak or flickering, or if you see any blue or green streaks in the flames, it indicates that the gas isn’t fully combusting. This issue can easily be overcome by having an HVAC technician maintain your furnace and clean the burners.

4. Cracked or Blocked Heater Exchanger

This is another issue that only occurs with gas furnaces, and it is by far the most serious problem on this list. If the heat exchanger is cracked, it will result in some of the hot combustion gases escaping, and that will prevent the heat exchanger from getting as hot as it should. This not only reduces the amount of heat the furnace produces, but it is also a serious health risk since it allows carbon monoxide to leak out into the ductwork.

Another possibility is that the outlets leading from the combustion chamber into the heat exchanger are clogged. When this happens, the hot combustion fumes will be trapped inside the chamber. The heat exchanger won’t absorb any heat energy, and the system will start blowing cold air even though the furnace is running. This is also a serious issue because it can allow flames to escape the combustion chamber and cause significant damage to the furnace. This situation also poses a major fire hazard.

If you’re having any issue with your furnace or heat pump, you can count on our team at Texas Pride Heating & Air to get it fixed. In fact, we offer a full range of heating, cooling, and indoor air quality services, including installation, repair, and maintenance for both residential and commercial customers in Southlake and the surrounding areas. To receive more information or schedule a heating inspection, contact us today.

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