Notice to our Customers: The safety of our customers and staff continues to be our #1 priority! Please click here to see our safety measures. If you have any questions or concerns, please don't hesitate to contact us.

3 Things to Check When Your Heater Blows Out Cold Air

man adjusting thermostat

On a chilly day, the last thing you want is to come home to a broken heater--but low and behold, you turn on your system, and cold air is coming out of your vents! Fortunately, there’s always a solution, and if your heater is blowing out cold air, you might not need a technician to solve the problem. Before picking up the phone, there are three crucial items you should check first.


If the air coming from your heater is cold or barely warm, you can try these easy troubleshooting steps before calling a technician.

1. Check your thermostat settings.

Make sure you’ve set your thermostat to AUTO, rather than ON. Here’s the difference:

  • AUTO: The system will only circulate air when the furnace is warming it.
  • ON: The system will continuously circulate air even when the furnace is not warming it.

2. Replace or clean your system’s air filter, depending on the type.

If your air filter is clogged with dust, dirt, and other particles, your heating system will lack the airflow it needs. Without enough airflow, the system will overheat. At that point, the high limit switch will shut off the burners to prevent a dangerous problem, such as the heat exchanger cracking.

3. Wait just a little longer.

If you haven’t used your heater in a long time, it might take some time before the air coming out of your vents feels warm. Why? Even if your furnace is working correctly, the air it warms has to travel through chilly ductwork, and it can lose a lot of heat along the way. Once the cold ductwork heats up, the air flowing through it will retain its heat better.

Give your system another 30 minutes or so and see if there’s an improvement. You can check your thermostat to monitor your home’s temperature changes in the meantime.


If you’ve tried the steps above, and your heater is still blowing out cold air, it’s time to shut your system off and contact a technician. You’re most likely dealing with a problem that involves one or more of the following:

  • Your furnace’s ability to ignite
  • How efficiently your furnace is burning fuel
  • Leaks in your ductwork

These issues are best handled by a professional to get the best long-term solution and avoid serious injury. After all, if you own a gas, oil, or propane furnace, you’re dealing with flammable substances and fire, which can be a dangerous combination in the wrong hands.

Having trouble with your heating system? At 1st Home & Commercial Services, our technicians provide top-notch service and reliable heater repairs to ensure that your equipment is operating efficiently and safely: (512) 957-2992.

Related Posts
  • What to Expect During a Heating Maintenance Read More
  • 6 Summertime Electrical Safety Tips for The Whole Family Read More
  • What To Do When Some Rooms Are Always Too Hot Read More