5 Reasons Why Your Furnace Is Not Working

Technician fixing a furnace not working

Is your furnace not turning on? Many homeowners discover that their furnace is not working when they need it most.

Assuming your furnace has been properly maintained, the problem is most likely a very simple fix that will not require the help of a professional.

If your furnace is not turning on you should first check if the filter is clean. Dirty filters cause insufficient airflow and can prevent the furnace from starting. Other reasons it won't start can stem from improper thermostat settings, forgetting to turn on the gas line, or faulty pilot light. 

Now that we know the common reasons why a furnace is not turning on, we will dive deeper into each reason and what can be done to troubleshoot.

First, it is essential to know the kind of furnace that is in your home. Most homeowners have a forced-air gas furnace, which is what we will be troubleshooting in this blog. 

Top 6 Reasons Your Furnace May Not Be Turning On

There are several reasons why your furnace may not be igniting. Below we list and discuss six of the main reasons why your furnace may be not turning on, as well as things that you could try to troubleshoot the problem. 

1. There Is An Issue With Your Thermostat

Although this may seem obvious, be sure your thermostat is set to heat and that it’s actually colder in your house than the temperature the thermostat is set to.

If it is neither of these reasons causing the issue, try turning the fan switch to “on” to force the furnace to start blowing air. If your furnace still refuses to turn on, check your programmable thermostat for an error code.

Often, newer electronic thermostats will display an error code if something is wrong. Check the display and see if it tells you what the problem is.

If it still doesn’t work, after you have tried all of those options, the problem is probably slightly more tricky than a simple thermostat fix. Continue reading to learn what some other causes may be. 

2. There Is An Issue With Your Gas Line

First and foremost, verify that the gas is turned on. You can check this by examining the shut-off valve which is outside.

Another easy way to tell if the gas is on and working properly is by starting another gas-burning appliance, like the stove.

If it seems like the gas line is not the issue and the gas is flowing to other appliances, check to make sure the gas supply to the furnace itself is open and clear.

If the gas supply to the furnace is disrupted, your furnace could potentially be lacking the amount of fuel necessary to ignite.

Finally, if you smell gas or believe there is a leak, evacuate your home immediately and call a professional to evaluate the emergency issue.

3. Your Furnace Is The Problem

Your furnace could also be the cause of the problem. The switch inside the furnace could have accidentally been switched off, so be sure the power is turned on. Even if you have a gas system, it uses electricity and must be turned on. There is a power disconnect switch by the furnace.

You can also check the breaker to make sure the power to the furnace has not been tripped. If it has been tripped, be sure to turn it back on. However, if it continues to trip, call an HVAC technician because something is wrong.

4. There Is Something Restricting Air Flow

Is your furnace working in some parts of your home and not in others? If so, the reason why your furnace may not be turning on could be because there is something that is blocking your air ducts and restricting airflow.

Make sure to take look at your furnace's ductwork and check to see if there are sufficient gaps between sections. One thing that you could do is seal the gaps that you see with duct tape (we recommend using a metal tape, as using any other type of tape may lead to potential leaks).

5. You Need To Change Your Air Filters

One of the easiest solutions to fix a broken furnace is changing the air filter.

If routine filter changes have not been completed and your vents and registers are completely clogged, this can greatly impair the furnace’s airflow.

First check to make sure the furnace filter is clean and has been recently changed, then be sure to make sure all vent registers are clear of furniture and other blockages. 

If this does not solve the problem, you may need to hire a professional company to clean your air ducts if the airflow is still obstructed.

6. You Have a Faulty Ignition Sensor (Pilot Light)

The pilot light or ignition sensor is usually the most common issue when your furnace will not ignite. This is typically the problem if you can hear your furnace click on but it does not fire up.

A faulty or dirty ignition or sensor is a relatively easy fix, so follow these steps, and you may be able to solve the problem yourself. 

First, you need to turn off the gas in the furnace. Then, remove the front panel to find the ignitor or ignition sensor. This is typically located near the burners.

If the sensor or ignitor is dirty, it will need to be cleaned. Remove it with a screwdriver and clean it while being careful not to break it. 

When you are finished, replace it exactly the way you found it. Put the front panel back on, turn on the gas, and then turn the furnace back on. 

Turn up the temperature on your thermostat to see if your furnace will now fire up. 

If this is the first time you’re attempting to light your gas furnace this season, it is important to know that a furnace ignition with a standing pilot light may take a while to light depending on the length of the gas line and how long it takes the fuel to reach the pilot light.

It may take a few minutes to start running even after being lit, so be patient. The thermocouple needs to get hot first, but theoretically, your furnace should start to work now.

Signs That You Need To Repair Your Furnace

Some signs that you need furnace repair include the following:

  • Your furnace is exerting odd unpleasant smells
  • Your furnace has a water leak
  • You can't turn on your furnace unit
  • There are uneven hot and cold spots throughout your home
  • There has been a spike in your utility bills
  • Your thermostat is making strange noises
  • Your furnace has a gas leak

When to Call a Certified HVAC Technician?

If you have determined it is not one of these problems, or you know that it is the motor or wiring causing the issue, you should call a professional furnace contractor to service your furnace and not attempt to resolve the issue on your own. Instead of asking yourself "why is my furnace not kicking on," give our team a call. 

Call now or click on the button below to schedule a service today.

We understand the inconvenience a broken furnace can cause when you need it most, so don’t wait any longer! 

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