Not Blowing hot air

Why Is My Furnace Not Blowing Hot Air? [Easy Troubleshoot]

ByYogesh Kunwar

Disclaimer: The information provided makes no claims, promises, or guarantees about the accuracy, completeness, or applicability of the content. It is the sole responsibility of the reader to assume this risk.

To be honest it’s kind of frustrating especially in the cold winter having a furnace not blowing hot air. Owning a furnace blowing cold air instead of hot sounds crazy when you invest a chunk of money to stay comfortable inside.

Every one of us relies upon HVAC to help maintain the warmth and live comfy, but having the “electric furnace not blowing hot air? Or, gas furnace not blowing hot air?” is worthless. For sure, no one of us doesn’t want to get stuck shivering inside on a cold evening!

Is there something to be alarmed about? Why is my furnace not blowing hot air? How can I fix it?

The simple answer is: We can’t be 100% sure, it depends on your situation.

Most of the time, there might be an issue that can be fixed by yourself. Indeed, for that what we can do is share with you the troubleshooting ideas to fix your furnace that blows hot air instead of cold. In some cases, you yourself could do the repairs but,

It’s best when a system is inspected and repaired by a professional.

But before contacting a pro try these simple furnace repairs at home that you can do by yourself.

Furnace Not Blowing Hot Air Most Common Problems

Quick answer: Here are a few “furnace not blowing hot air easy fix tips” you can try at home by yourself before calling a pro.

  • Inspect the thermostat batteries & replace the damaged ones.
  • Make sure the thermostat fan setting is set to AUTO instead of ON.
  • Make sure the gas supply is on to avoid the downfall in thermostat temperature.
  • Do inspect the elements that are vulnerable to clogging.
  • Check whether the duct might be subjected to a leakage.
  • Just check if someone had forgotten to switch on the blower motor board after the repair.

Even after checking all these above-listed troubleshooting tips if you still find your furnace blowing not blowing hot air. No brainer, you should make a call to an HVAC Professionals!

1. Thermostat Setting Issues

You might wonder; From where should I start repairing? Why is my furnace blowing cold air instead of hot? A thermostat system should be your first device for repairing your furnace because every professional begins to fix the furnace by checking their setting whether properly seated or not. It’s one of the main important devices to heat your home.

HVAC is notified by the thermostat signals to turn on your heat when your home reaches the temperature limit to start the heating cycle. When it is turned on, the signal received on the control board initiates the turning on the furnace blower. This is the point where the problem could start.

To solve this just simply turn the fan switch from ON to AUTO.

After the AUTO mode is turned on, it allows the furnace to blow hot air into your home when it is activated or used.


2. Heating System Issues In The Furnace Itself

  • For Gas Furnace: For a gas furnace not blowing hot air, check the gas supply line valve whether it’s open. For older furnace models, inspect if the pilot light is torched & for newer models check the electronic starter if it’s receiving power.
  • For Electric Heater: For the electric furnace not blowing hot air, reset the circuit breaker checking the electrical panel if tripped. If you find the circuit breaker tripping in the control unit, there might be a short circuit in the system. In such a case, It’s best to call the HVAC pro for the repair.
  • For Heat Pump: There could be a case heat pump blowing cold air, because of which its auxiliary heat strips might go wrong or the refrigerant level might be exclusively low. Contact the HVAC expert to fix it.

3. Problem With The Pilot Light Being Out

Just follow the how-to instructions that are located in the furnace manual,

  • Light again the pilot light
  • Inspect whether the furnace’s gas valve key is on
  • Make sure the pilot light is clean
  • Substitute another thermocouple

You yourself can change the thermocouple at home itself by buying a replacement for it. But, if you are not aware of how to install this, approach the technician.

4. Unchanged Filter

Well considering all furnace problems; filters and thermostat setting issues are the most frequent furnace problems that result in the furnace not blowing hot air. People might ask, why is my furnace not blowing hot air? In this case, a clogged furnace filter can’t allow airflow properly up to the mark and makes your furnace work much harder.

What exactly happens is; clogged filters holding dust and dirt don’t allow proper airflow and it results in overheating of the heat exchanger because of which switches shut down too quickly. Consequently, your house will not warm up!

Note: Always turn off the system before changing the filter or working on the thermostat.

If you are familiar with this, you yourself can change the filter. For support, you can go through the manual that shows where the filter is positioned and how to replace it.

5. Simple Flame Sensor Issue

The old or dirty flame sensor will also cause the furnace to blow cold air instead of hot. Out of the most common issues, this is the furnace not blowing hot air easy fix!

A clean flame sensor is necessary for the system. If it gets dirty or old, it could be noting down inaccurate temperature readings causing the temperature to be too low. However, the fan running causes the cold air to blow and makes you shiver while living inside your house.

Regular maintenance must be done to work your furnace properly.

Indeed, If the flame sensor is dirty it will cause your furnace to cycle off.

6. Lacking Gas Supply

Gas furnace not blowing hot air?

Make sure the gas is on. The gas supply had been cut off as

  • someone might have turned off a gas valve
  • the system might shut down itself for safety measures

If this is the issue then the gas furnace fix depends on how old your furnace is. If you own an old furnace there will have a pilot light. Just remove the front panel and burner cover, to inspect and make sure it lights up.

7. Mixing Of Outside Air


The pipe that carries the warm air all over your house is possible to wear and tear. Especially because the ducts are placed outside the warmth radar of your house which leads to the chances to be exposed to extreme temperature changes all the time. However, changes in temperature affect the weak areas of the duct turning into actual leaks. The few most common risks to cause duct leaks,

  • Unsafe transport and lazy packaging(unhooked) could develop leaks in the ducts when received
  • Duct repair might need to be re-fixed 
  • Poor ductwork fractures that are not screwed together properly

Furnace blowing warm air not hot? The outside air mixing with the warm air of the duct results in a decrease in the temperature of the air coming out from your furnace. Eventually, the cool air blows out instead of the hot air in your house.


Final Words

There could be plenty of problems that could make way to enter cold air inside your heating system. A few of the issues could be fixed at home with a little extra hard work and knowledge. But, besides basic inspection and checkups if you are not able to troubleshoot the problem it’s best to hire an HVAC Professionals. The top HVAC Pro services of the team are as follows if needed.

HVAC Professionals Contact Information

Call the professionals to get the work done properly & quickly!

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