Revised:
March 15th, 2023
When your furnace is blowing cold air instead of warm, it might be due to a small, fixable issue, or it could be a sign of something more serious. In this video, we’ll explore the possible causes and potential fixes for this problem.
Hi, I’m Luke from Fire & Ice. As a residential sales professional, I have helped hundreds of Central Ohio homeowners diagnose problems with their HVAC systems. At Fire & Ice we believe in giving our customers as much information as they need. In this video, we’re going to discuss potential reasons why your furnace is blowing cold air.
Your Thermostat
The first place to start is with the brains of the system, your thermostat. Make sure the thermostat is set to Heat and make sure the fan is set to auto. The problem could also be with the wiring of your thermostat. If the wires are shorted, losing communication with the furnace, you may need to call a professional.
Dirty Air Filter
An easy item homeowners can maintain is their furnace filter. Air filters trap dirt, dust, and other contaminants, cleaning the air and helping to keep the ductwork and furnace clean. If they are left in place too long, they become choked, which restricts airflow to the furnace. This causes the furnace to work harder and can cause the heat exchanger to overheat and shut off too quickly.
A Lack of Airflow
Furniture blocking return air registers can starve the furnace of needed air, causing less airflow and decreased temperatures. Also, if the return air ducts are too small, the furnace will not be able to take in the required amount of air causing your heater to blow cold air.
Leaky Ducts
In a typical house, about 20 to 30 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. Warm air could be deposited in the basement before it has the chance to reach the far rooms of your house. The holes in your ductwork can also allow cold air from unconditioned rooms to enter the vents.
Flame Sensors & Heating Strips
And finally, a modern furnace without a pilot light relies on flame detectors to ensure the successful completion of a heating cycle. If the flame detector is covered in dust, dirt, or grime, you will quickly lose heat and your gas furnace will start blowing cold air. Electric furnaces and air handlers can have a similar problem. They create heat through the use of heat strips. If the strips go bad, the blower will still run, blowing cold air.
What you can do
We always recommend major maintenance be performed by a professional to maintain your warranty, for your safety, and to ensure the job is done right. But you can do a few things to help solve your issue. Ensure your thermostat is set correctly and take note of any out of the ordinary performance issues. Change your air filter regularly. A clogged filter can result in cooler temperatures and reduced airflow. And finally, look and feel for leaks in your duct work and seal them. Leaks in your ductwork can allow cold air to mix with your heated air.
What are the next steps
I hope by now you have a better understanding of potential reasons why your furnace is blowing cold air. If you’d like to schedule a service appointment for your system, click the schedule service button at the top of the screen. Thank you for watching and we look forward to making your day better.
Further Reading: Reasons Why Your Furnace Is Blowing Cold Air
