A furnace is supposed to blow hot air and keep everyone in your house warm during the winter. But if it starts to produce cold air instead of hot air, it will obviously frustrate the homeowners. Moreover, if it happens when the temperature outside is freezing, it can make the situation worse.
Why Is Your Furnace Blowing Cold Air? — The Causes & Their Solutions
When your furnace or heating unit blows cold air, it indicates that something inside the unit is preventing it from producing hot air. This can happen for several reasons. For example, neglecting the repair for years can make the unit function less efficiently and cause this heating issue.
Apart from this, if you have an older furnace system, it can happen due to a malfunction in the ignition light. Usually, it happens due to a draft or issue with the thermocouple. Again, your furnace can blow cold air when you have a faulty blower.
As this topic requires in-depth discussion and, if the situation isn’t handled properly, can severely impact your family’s comfort, here are the top 5 common causes of a furnace blowing cold air:
5 Common Causes of a Furnace Blowing Cold Air
1. Issue with the Thermostat
As soon as you notice that the furnace is blowing hot air, the first thing you should do is check the thermostat settings. Sometimes, just switching the thermostat’s settings can fix the issue.
When the thermostat setting of your furnace is set to “On”, this will blow air constantly, even when the furnace isn’t producing hot air. Because of this, the furnace will blow cold during the idle times. To stop the heating unit from producing cold air, you must change the furnace thermostat setting from “On” to “Auto”. This will ensure that the furnace will only blow air when it is actively heating the indoor environment.
Apart from this, when the temperature setting is set to low, it can make you feel that it is producing cold air. To combat this issue, you’ll have to check the temperature on the thermostat. If you find out that the temperature is lower than usual, you’ll have to increase it to a desirable temperature. As a result, the furnace will start reheating the air again.
2. Clogged Furnace Filter
When the furnace filter is clogged, it restricts the airflow required to produce hot air. This eventually causes your system to blow cold air. Again, when the furnace is not receiving enough airflow, the system overheats, resulting in frequent shutdowns as a safety measure.
If you live in an area or city where the level of air pollution is very high, your system’s furnace will get clogged very quickly. In this case, you must change the furnace filter earlier than usual. However, if you’re in a place where the air quality is decent, you can replace it every 2-3 months.
While using the air filter, you’ll have to ensure that you’re installing the right-sized filter. For further protection, you can use HEPA or MERV filters. However, before installing such a high-rated filter in your furnace, you’ll have to check its compatibility with the furnace.
3. Leaks in the Ductwork
If your furnace blows hot air initially but then starts to blow cold air, this can happen due to leakage in the air ducts. When there is a leakage in the furnace ductwork, the warm air escapes through the holes, causing the cold air to flow through the furnace vents.
To solve this issue, you’ll have to look for cracks and holes in the furnace ductwork. For this, you can use a smoke pencil. When it is placed near the furnace ducts, any hot air escaping through the holes will disturb the smoke pattern and allow you to identify the leaks.
Apart from the smoke pencil, you can use smoke machines or airflow meters. However, the best way to identify leakage is to call an HVAC contractor. They will check the air duct thoroughly and look for leaks.
You can consider adding insulation to the air ducts and increasing the overall insulation of your house.
4. Overheating Issue
When it is overheating, your furnace can blow cold air. This is usually due to faulty parts and poor maintenance. To prevent further damage to the unit, the furnace can start to blow cold air.
To prevent overheating, the first thing you’ll have to do is clear the vents. You must ensure that all the return and supply vents in your space are open and not obstructed by objects such as curtains and furniture.
Apart from clearing the vents, you’ll have to do regular furnace maintenance. During maintenance, an HVAC professional will replace the worn-out parts and allow the furnace to operate smoothly.
5. Low Fuel Supply
Your furnace can stop producing hot air due to a low fuel supply. To combat this issue, you’ll first have to check the furnace’s fuel level.
If you find that the fuel level is low, you’ll have to refill it with the fuel you use. The best way to prevent this issue is to contact a local gas supplier for a timely refill.
Conclusion
A furnace blowing cold air can be frustrating, but identifying the cause and addressing it promptly can help restore comfort in your home. From thermostat settings to more complex issues like overheating or blower motor failures, understanding the root cause is key to finding the right solution. Some of these furnace issues can be fixed by simple repairs, while others may require hiring an expert HVAC professional to repair them professionally.
By following the troubleshooting tips above, you can ensure that your heating is operating efficiently and keeping your space warm and comfortable during colder days.
