Why Is My Furnace Blowing Cold Air?

Do you have a furnace blowing cold air?

If yes, you are not only losing money but also you and your family are at the risk of catching a cold. 

A furnace blowing cold air in a home is an indicator of one of the various possible issues; dirty flame sensors, interrupted gas supply, malfunctioning air filters, damaged pilot light, or clogged condensate lines. 

Usually, the furnace issues can be resolved by cleaning or replacing the damaged components.

However, you should first know why your furnace is blowing cold air instead of hot air.

This article shares useful information to help you find the answer. 

Reasons behind the Furnace Blowing Cold Air

Damaged Pilot Light

It is recommended to first inspect the pilot light in your gas system if you find your furnace blowing cold air.

The purpose of a pilot light is to ignite the burners that help the system keep producing heat.

Usually, older gas furnaces have a pilot light issue.

In this case, follow the instruction kit that you received with your furnace to re-light its pilot.

Dirty Flame Sensor

Grime and dirt are common issues when it comes to the furnace not working properly.

Furnaces that have flame sensors usually do not have a pilot light and these rely on the flame detectors to maintain the heating cycle. 

Flame sensors, covered in grime or dust, lose the heat quickly, resulting in a furnace blowing cold air.

Hence, it is recommended to clean the flame detectors in the furnace frequently.

You can hire an HVAC expert to clean and sanitize these components to restore the furnace heating process. 

Restricted Airflow in Filters

Air filters in the furnace must be cleaned and free of soot, grime, and dust.

These particles block the airflow in the furnace and lead to overheating and long heating cycles.

In this case, you should replace the air filters on a regular basis.

Replacing the dirty filters will help avoid airflow blockage to the furnace and the unit will not overheat. 

Interrupted Gas Supply

If your furnace is blowing cold air, there might be an interrupted gas supply in your home.

Most of the furnaces are designed to automatically stop working if not getting adequate gas supply to carry out its standard heating process.

Unfortunately, you cannot fix this issue yourself.

It is suggested to call a professional HVAC expert to do a gas furnace repair after checking the gas supply.

Clogged Condensate Lines 

Nowadays, the furnaces are fitted with condensate drain lines to stop moisture.

Hence, any blockage in the condensate lines can deactivate the burners, causing the furnace to blow cold air.

Poor Ductwork

The cracks and holes in the ductwork often cause furnace problems.

These openings let the cold air enter the air ducts from the attic.

Duct sealing can help the warm air enter the vents more efficiently.

Final Thoughts

We hope it will be easier for you now to check the possible reasons for your furnace blowing cold air instead of hot air.

For more information and assistance, our certified and expert HVAC technicians are at your service. Call us today!