Why Is My Furnace Blowing Cold Air?

Where would we be without the awesome power of furnaces? Unfortunately, when your furnace stops working, it can put a serious damper on the comfort, functionality, and safety of your home. 

If you’ve noticed cold air blowing out of vents when your heat is on, it’s time for you to call for repairs. But why would a furnace be blowing cold air? And how do you fix a furnace that blows cold air? 

If your furnace is blowing cold air, read on below! We’ll discuss the common causes of this problem and how a professional can address them.  

Experts Answer: Why Is My Furnace Blowing Cold Air?

There can be multiple causes for why a heating system would suddenly blow out cold air instead of hot. 

Some common reasons are: 

  • Old age 
  • Dirty filters 
  • Faulty pilot light 
  • An overheated system 

An experienced technician can inspect your furnace for these issues and tell you why your furnace is blowing out cold air. 

Old Age 

Like with any piece of equipment, when your furnace reaches an older age, it begins to malfunction at a much higher rate than a newer machine. 

A typical furnace has a lifespan of about 10 to 15 years. When your furnace begins to approach the older end of that spectrum, its performance will naturally decline. 

Sometimes, the internal components that are responsible for creating the hotter temperatures will fail to kickstart. Other times, your vent system may simply have less power than it used to, which means that hot air will struggle to travel through the air duct system into your home. 

Fortunately, there are ways to prevent and mitigate damage to your furnace. 

Performing annual maintenance on your heating system will help your heater work properly into its old age. If you begin maintenance early, you keep all of its internal components working well and in good health. 

If your heater is pushing the upper limit of its lifespan and you think you want to purchase a new heater, our heating experts at TSS Home Comfort can guide you through the entire process to find a good fit for your home and your budget. 

Dirty Filters 

Dirt can inflict a lot of damage on your furnace system. While a little dust here and there may not seem like a big deal, too much can prevent hot air from blowing into your home. 

How? Your filter is the primary defense between the dirt in your home’s air and your heating system. The filter does a great job at catching most of the dirt as air drifts from your home back into your HVAC system. 

However, when the filter is too clogged, the dirt in your home’s air will make its way past your filter and enter your home’s ductwork system. 

It then travels through the ducts and sticks to your HVAC system. When dirt clings to your HVAC system, it can block airflow over your heat exchanger, resulting in a tripped furnace. 

Faulty Pilot Light 

Thankfully, having a faulty pilot light is an easy problem to solve. 

The pilot light is a small, blue flame in your furnace. When this light is out, your furnace has no way of heating the air in the system. As a result, your HVAC system has no choice but to blow out cold or room temperature air when you turn the machine on. 

While this may seem like a problem you can solve yourself, it’s much safer to call the help of a professional. 

Your furnace is a complicated system that holds a lot of noxious gasses. These gasses can lead to sudden combustion or even a deadly fire with an inexperienced hand.

For safe, effective service, call TSS Home Comfort. 


When too much strain is put on your heater, the system can overheat and shut down. 

An overheated furnace can happen for multiple reasons. There could be a leak or a hole in your air duct system, which means that your furnace must do twice the work to push the same amount of hot air into your home. 

Other reasons could include a dirty filter or even old age. The truth is, there’s no way to know what the reason is until you call a professional. 

Call us today to survey your home’s heater system – we’ll help fix the current problem and advise you on ways to protect your home from fires by repairing or installing an IR flame sensor in your furnace.

Reach Out to TSS Home Comfort for Help

Is your furnace blowing cold air instead of heat only at night? Maybe your furnace smells like gas or won’t shut off. At TSS Home Comfort, we’re here to deliver exceptional furnace repairs – no matter the problem. 

With a fleet of fully licensed, vetted, and passionate technicians, we’ve been honored to serve the Treasure Valley region for over 35 years. From installing electric furnaces to providing seasonal tune-ups to handling extensive repairs, we’re excited to arm your home with the most exceptional heating and cooling technology possible. 

See why TSS Home Comfort is the best choice for furnace repair in Treasure Valley. Pick up the phone and Give Us A Call Today to book your next appointment.