During the winter months, no one wants their furnace blowing cold air.   However, this occurs more often than people think and can result from a plethora of different issues. Here are some of the common and uncommon reasons we see furnaces blowing cold air.

Common Reasons:


One of the main culprits of cold airflow is an improperly set thermostat. Often, other individuals in one’s home or workplace change the thermostat’s setting from “Auto” to “On,” thinking that it will lead to the warmer or colder temperatures they desire. However, what this is doing is telling the fan to continue to blow air even if the furnace is not actively heating; this will result in non-heated air circulating your home as well as a higher electric bill.

In addition to incorrect settings, your thermostat could be no longer operating correctly, it may have a bad battery, or possibly have been incorrectly installed if it is a recent replacement. While replacing the batteries is a simple DIY job, ensuring your thermostat is fully functional and compatible with your furnace is something that may require a professional’s touch.

Air Filters

Another common issue is clogged air filters, causing your system to overheat and turn the burner off, which will result in your system flowing non-heated air throughout your home. When this happens, it is fixable by replacing your filter and returning your system to its normal working state. In some instances, you may need to relight the pilot light manually. If this is a job you are not comfortable with, do not hesitate to reach out to us for assistance.

Other Issues:


Pilot Light/Ignition Issues

Your furnace’s pilot light may have gone out, or your electronic ignition system may not be operating correctly. Some older furnaces have continuous pilot lights, and it is possible that the light has been extinguished and needs to be relit manually. For more modern systems with electronic ignition, your system likely has a malfunction, and with units driven by computers, your system may need rebooting.

Valve Issues

The value that allows gas into the system may be faulty and not properly allowing gas to flow into the furnace, giving your furnace no fuel to ignite. If you believe this to be an issue, we suggest you contact us for proper repair.

Duct Work Issues

There is potential for loss of heat through inadequate or porous air ducting. When there are holes or loose fittings, you can end up heating places where it is not needed, such as an attic or behind walls. Consider contacting an expert to diagnose your system if you think this may be a possibility.

Malfunctioning Flame Sensor

Your furnace likely has a flame sensor responsible for telling the system when the igniting flame is on versus off. If this isn’t operating properly, the sensor may believe the flame is on when it is out, or it can keep causing the burner to turn off when it should be on. A common symptom of this issue is when your furnace turns on and blows warm air but begins blowing cold air shortly after ignition.

The Final Verdict

Regardless of what may be leading to your furnace blowing cold air, we can all agree it is an undesirable problem to have when we need it the most. If you find your home or business suffering from this problem, don’t hesitate to contact us for an appointment at (812) 683-0675 to diagnose your system. In addition to repairing the heating issue, it can often lead to cost savings that may have been hindered by a previously inefficient system.