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Three Common Furnace Problems


Troubleshooting furnaces can be difficult when you don’t know what to look for. For example, you might know that your furnace is making strange noises, not turning on, or not producing enough heat to keep up, but you might now know why. Luckily, we can help. In this blog post, we talk about three common furnace problems and what to do if they are happening. If you have any questions after reading this blog post, feel free to leave a comment below. We are here to help.

An HVAC Technician Checking For Common Furnace Problems

1. Clogged Filter

If you notice that your furnace doesn’t seem to be able to keep up during the winter or won’t produce heat at all, check your furnace’s filter. In our blog post “The Importance of HVAC Filters,” we define filters as “devices that filter particles in the air and clean it.” This is true, and when they aren’t changed frequently, your HVAC system is bound to run into problems. We recommend you change your filters once a month, although this can differ depending on multiple factors. For example, the thicker the filter is, the less often you need to change it. You only need to change a four-inch filter every six months. No matter how thick your filter is though, if you have pets, live in a dusty environment, or have any health conditions, we recommend you change your filter more often. Not changing your furnace’s filter can result in the above problems or damage to your filter. We talk more about HVAC filters in our “The Importance of HVAC Filters” blog post.

Clogged furnace filter
A clogged furnace filter

2. Dirty Flame Sensor

When you have a dirty flame sensor, your furnace may power on for a moment and then shut right off. This happens when your flame sensor, a component of your furnace that usually looks like a little bent iron rod and is used to detect if your furnace is producing a flame, gets dirty. When your flame sensor gets dirty, it stops sensing the flame and turns off. The reason why furnaces have flame sensors is to prevent gas leaks, which can lead to carbon monoxide build-up and fires.

Thankfully, you can clean your dirty flame sensor as long as you have steel wool and a screwdriver

Here are the steps: 

  1. Turn off your furnace. You should always turn off your furnace before working on it.
  2. Take off the top door of your furnace. If it is screwed in, use a screwdriver to gently unscrew it.
  3. Locate your flame sensor. It should be in front of your furnace burners and on the opposite side of your furnace ignitor. If you cannot see your flame sensor or cannot access it easily, then we recommend you call an HVAC technician to clean it. Some flame sensors can be difficult to get to, and trying to clean them yourself can be more of a hassle than it’s worth. If you can get to your flame sensor, proceed with the next step.
  4. Your flame sensor will likely be held in by a screw. Unscrew it and take your flame sensor out carefully. Do not disconnect it from any wires.
  5. Now, you can clean your flame sensor. To clean your flame sensor, apply firm pressure on it with steel wool and wipe it down. Do not scratch the rod, or dust will stick to it faster.
  6. Once you are done cleaning it, place your flame sensor back into your furnace and screw it back on. Test your furnace to see if cleaning your flame sensor resolved your problem.

If cleaning your flame sensor doesn’t resolve your problem, then it might be worth checking if other common furnace problems are causing it, such as a clogged filter or dirty burners. If you are not able to find a solution to your problem, we recommend calling a reputable HVAC company. 

A furnace's flame sensor
A furnace’s flame sensor

3. Dirty Burners

If you hear any strange noises, such as booms and rattling noises coming from your furnace, or notice that your energy bills are higher than normal, your furnace’s burners might be dirty. A furnace burner is a part of your furnace where air and fuel combine to create heat. A furnace burner’s flame should always be blue. If it is any other color, such as yellow or orange, your furnace is not working correctly. Unfortunately, we do not recommend cleaning your furnace burners. If you live in Jefferson County or the surrounding areas, we would be happy to clean them for you. In fact, the maintenance plan options in our Partney Comfort Club all include cleaning furnace burners so that your furnace works when you need it most. 

Furnace burner's flame
What a furnace burner’s flame should look like


In this blog post, we discussed three common furnace problems and how to fix them. While not all common furnace problems can be fixed without the help of an HVAC technician, some of them can be, like clogged filters and dirty flame sensors. As always, we recommend constantly maintaining your HVAC system to prevent future problems. Are you having furnace problems and live in Crystal City, Festus, or the surrounding cities? Give us a call! Our phone number is 636-475-9384. We offer free estimates and would be happy to help you. 

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