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7 Reasons Why Your Furnace is Blowing Cold Air & How to Fix It

If recent winters have taught us anything, it’s that we need to be prepared. Cold weather comes unexpectedly, and you never know how long it will stay or what conditions will come with it.

Dallas-Fort Worth homeowners are becoming more aware of the importance of having a reliable furnace, so when your system blows cold air, it can cause you to panic.

Here are seven common reasons why your furnace is blowing cold air and how you can resolve the issue — either with a DIY method or by calling an HVAC professional for heating service.

Restricted Airflow

If the air filter is dirty and clogged, airflow to the furnace is restricted. This makes your system work much harder and potentially overheat, at which time it will begin blowing cold air.

Replace your air filter to restore proper airflow, and change the filter at least every three months to avoid this issue in the future.

Incorrect Thermostat Settings

Check to make sure your thermostat is set to “Auto” instead of “On.” Kids, guests, or anyone in your home can accidentally switch the system mode.

When the fan is on, it will constantly run and blow air instead of shutting off when the furnace cycle ends. 

Damaged Pilot Light

The pilot light in a gas furnace is designed to ignite the burners that create the heat. It’s common to have issues with the pilot light, particularly on older units. If it’s out, you can do two things to investigate the issue:

• Verify the gas valve is open and that the pilot light isn’t too dirty.
• Read the user’s manual for instructions on relighting the pilot light. 

If you relight the pilot light but it goes out again, the problem may be related to a bigger issue, like thermocouple failure or other ignition problems. In that case, you should call a professional HVAC technician. 

Dirty Flame Detector

The flame detector helps ensure the completion of a heating cycle. When it gets dirty, the burner won’t turn on, which cuts off heat production. Because these issues don’t affect the fan, the system will continue pushing unheated air through the vents.

A simple cleaning should fix the issue, but if you have trouble identifying the parts in your furnace, go ahead and schedule HVAC service. Clogged or worn parts are easily preventable with annual heating maintenance.  

Clogged Condensate Lines

A condensate line helps remove water from the condensing unit, but it can become clogged. A clog in the condensate line trips a switch to prevent the burners from igniting. Cutting off the heat reduces the amount of condensation formed, leading to cold air being blown into the home.

A specialized tool is used for clearing condensate lines, so you must call an HVAC professional. Once the line is cleared, the system is reset to function properly.

Damaged Ductwork

Holes or cracks in your ductwork allow cold air from the attic to enter the air ducts. Enough cold air intrusion will make its way through the vents throughout your home.

You can venture into your attic and investigate any visible ductwork to see if that’s the problem. Call an HVAC technician if you suspect it’s part of the issue but are unsure. They have special equipment to inspect the ductwork and resolve the issue.

Low Gas Supply

A gas furnace can’t generate heat if it’s not receiving enough gas to perform. You can check to ensure the gas valve is open, but beyond that, you will need to call an HVAC professional to safely investigate gas line issues in your home.

Gas lines should be regularly inspected to ensure they’re in good working order because they can become worn over time.

Call AirCo for Furnace Repairs in the Dallas-Fort Worth Area

Furnaces are susceptible to wear and tear during their life span, making it tough to diagnose and resolve heating problems yourself.

AirCo offers same-day service from expert technicians who provide comprehensive inspections and heating repairs. You get the courtesy and care of a family-owned company, and we never charge overtime, evening, or weekend fees. We care about keeping you safe and comfortable with little disruption to your home and schedule.

Contact AirCo online or call (817) 591-1225 now to request same-day heating repairs.