5 Common Furnace Problems and How to Troubleshoot Them

Introduction

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 five 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.

1. Dirty 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 air filter. One of the most common furnace problems is a dirty filter. If enough dirt and debris collects in it, then your HVAC system is bound to run into problems. A dirty furnace filter eventually leads to a clogged filter. When your filter becomes clogged, airflow is reduced. When airflow is reduced, your system has to work harder to keep up, and the efficiency of your heating system goes down.

We recommend you change your furnace filter 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, 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.

2. Dirty Flame Sensor

When you have a dirty flame sensor, your gas 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 detects if your furnace is producing a flame when gas is on, gets dirty. 

When your flame sensor gets dirty, it stops sensing the flame and turns off. Furnaces have flame sensors 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 the top door of your furnace off. 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, 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 has 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 dirty filter or dirty burners. If you are not able to find a solution to your problem, we recommend calling a reputable HVAC company. 

It’s important to note that some older furnaces do not have flame sensors and may just have pilot lights. You can tell if a pilot light has gone bad if it is cracked or discolored.

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 and suggest leaving that to a professional HVAC technician. If you live in Jefferson County or the surrounding areas, we would happily clean them for you. 

All of the maintenance plan options in our Partney Comfort Club include cleaning furnace burners so that your furnace works when you need it most. Our plans include routine maintenance that can help keep your furnace in tip-top shape and help prevent common furnace problems.

4. Faulty Thermostat

If you have a faulty thermostat then, unfortunately, it doesn’t matter how well your furnace is working. Your thermostat communicates with your furnace in order to control the temperature of a room. When your furnace is unable to receive instructions from your thermostat, then it doesn’t know what to do, and you won’t be able to control the room temperature.

Here are a few troubleshooting steps you can try:

• Replace the batteries. If the thermostat is battery-operated and not working, then the batteries may be dead. 
• Inspect the thermostat’s wiring. Loose or damaged wiring can prevent a thermostat from working. 
• Dust the thermostat. Dirt and debris can affect the thermostat’s ability to communicate with your HVAC system and misread the room’s temperature.
• Reposition the thermostat. If the thermostat is near a heat source such as a lamp, then it will not be able to read the room’s temperature accurately.

We cover three common thermostat problems more in depth in our blog post “Thermostats 101” that could cause your thermostat to stop working.

5. Tripped Circuit Breaker

A tripped circuit breaker will lead to your furnace not working. Most modern furnaces use electricity in some shape or form, even if they don’t use it for fuel. If you find that your furnace circuit breaker keeps tripping, think back on each time it has happened. Does your furnace share a circuit breaker with any other device? Did you hear unusual noises coming from your furnace before the circuit tripped? If you find that there is a pattern, then that could help figure out the problem significantly.

We do not recommend repeatedly resetting your furnace breaker as it may be tripping due to something being seriously wrong. Circuit breakers are safety features and are only, in theory, supposed to trip to prevent fires, overheating, and damage. It’s better to be safe than sorry until you start troubleshooting it.

Some things you can do to try to fix your furnace tripping your circuit breaker are changing your furnace’s air filter and checking around your return vents. Your return vents are vents inside of your home that pull air from your home and return it to your HVAC system. When they are blocked, your furnace is forced to work harder. An overworked furnace can trip your furnace breaker. Look around your return vents and check to see if anything is blocking them, such as furniture. If anything is, then remove them. Seek professional help if after going through the common troubleshooting steps, your furnace is still tripping your circuit breaker.

Conclusion

In this blog post, we discussed five common furnace problems and how to fix them. While not all problems can be fixed without the help of an HVAC technician, some of them can be, like dirty filters and dirty flame sensors. As always, we recommend regularly maintaining your HVAC system to prevent future problems. 

Are you having furnace problems and live in Herculaneum, Festus, or the surrounding areas? Give us a call! Our phone number is 636-475-9384. We offer free estimates and would be happy to help you with your furnace repairs.