Why Is My Heater Blowing Out Cold Air? | Custom Air System Skip to main content


It’s happened to most of us at some point. It’s the middle of winter, cold outside, and the air is brisk. You’ve been trying to use your heater sparingly because you’re trying to save money on your electric bill, but you broke down. You’ve turned it on, and suddenly it’s blowing nothing but cold air. Not what you need when you’re already freezing. But what would cause a heater to blow nothing but cold air? There are a couple of reasons.

Why is My Heater Blowing out Cold Air?

It Could Be Your Thermostat

One of the most common causes of cold air blowing out of your heater is a bad thermostat. It happens, thermostats do stop working, especially if the one you have is ancient. Unfortunately, the only way to fix this is to have a certified HVAC technician take a look.

There are also a couple of simple reasons your thermostat is causing your heater to blow cold air:

  • Your thermostat runs on batteries and they are dead or almost dead – while many thermostats only use batteries as a backup to their central power hook up, there are a few models that run on batteries only. Check to see if yours is one of these models and if so, replace the batteries.
  • Your thermostat is set to the same temperature or colder than the temperature in your home – if your home’s temperature is set on 60 degrees and it’s already 60 degrees (or colder) in your home, you’ll get nothing but cold air when you turn on your heat. You have to increase the temperature on your thermostat to above your home’s current temperature to get heat.
    Your Ductwork is Leaking
  • If your heating system installation wasn’t up to par or the ductwork in your home is older, you may have leaks in the system. A leak in your ductwork can allow cold air in, allow it to mix with your heat, and consequently, leave you with cold air. This is more common in older ductwork but can happen in areas where temperatures vary considerably which increases normal wear and tear.

You could also have a problem with the insulation surrounding the ductwork. Poor insulation increases the stress on the ducts, causing them to break down, but this can also happen if your insulation is older. If you suspect your insulation is to blame, or that your ductwork needs help, you should contact a certified HVAC technician for help.

Do you need heating repair in League City? Contact the experts at Custom Air Systems so we can make sure your heating system is in good, working status!

(281) 466-4297