Every winter comes with the need for heat, which is why HVAC companies are the heroes of winter. One of the most common calls we get in the winter is that their furnace is blowing cold air. Why is this? This could be because of a variety of different causes. Some more difficult to fix than others. Here are some top reasons and the potential solutions to why your furnace is blowing cold air.

Furnace Pilot Light

Dirty Filter

The airflow that goes into your furnace and then back out is very important in the redistribution of air. Clogged filters are what restrict this airflow. Without a clear filter, the furnace can overheat and turn off. It’s a simple solution–change your filter! If you’re not confident with a filter change, check out our Filter Fundamentals here.

Startup Delay

The first few seconds or minutes that the furnace is on may not be up to temperature yet. Heat takes longer to generate, especially during initial startup. It is recommended to wait at least a minute or two to ensure proper heating function of the furnace.

Clogged Condensate Line

Clogged condensate lines will prevent your furnace from igniting. If the furnace isn’t ignited, then just air is blowing through the vents. The clog should be cleared from the condensate to bring the furnace back to working order.

Damaged Pilot Light

If your furnace is older, your may have a faulty pilot light. This is the part of the furnace that provides the flame that lights the burners. If the pilot light is out, the system won’t operate efficiently, if, even at all. Sometimes the solution may be as simple as cleaning the pilot or flame sensor. If the flame still won’t hold, it may be time for a new pilot assembly.

Leaky Ducts

It’s not uncommon for ductwork to disconnect or crack. Warm air could be escaping in cracks or crevices of your ducts. Call a professional to seal your ductwork thoroughly.

Clogged Coil

Clogged Coil

The evaporator coil inside a furnace can collect dirt and debris over time. All air must pass by this coil before entering the supply duct. Therefore, if enough debris builds up on the evaporator coil, it restricts airflow entirely.


These are not all simple solutions, and more often than not, will require a professional to investigate. Poormans Heating & Air is a locally-owned HVAC company that services Northeast Indiana and Northwest Ohio.