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Furnace Problems: 10 Common Issues & Easy Solutions

furnace problems 10 common issues and easy solutions

Winter is coming, and with it comes cold temperatures. This means your furnace will be working overtime to make sure you stay warm. But like any machine, there are always going to be problems that pop up along the way. Avoid some of these common furnace issues and get back to enjoying crackling winter fires and hot cocoa instead of worrying about your furnace.

What are Common Furnace Problems?

When furnace problems arise, you want to make sure that they are fixed as soon as possible. The furnace is usually the largest energy user in your home, so when it’s not working properly, your energy costs will go up exponentially.

There are many signs that indicate when your system may need work done on it.

  1. Strange noises
  2. Furnace clicks but doesn’t turn on
  3. Dirty filter
  4. Failed condensate pump
  5. Failing furnace blower motor
  6. Failed ignitor
  7. Frequent cycling
  8. Furnace doesn’t heat
  9. Malfunctioning thermostat
  10. Blower continuously runs

Is There a Way to “Diagnose” a Furnace Problem?

Every year, hundreds of homeowners in Portland ask: What’s wrong with my gas or electric furnace? On newer gas or electric furnaces, it is possible to find a diagnostic code for what is going wrong with your furnace.

To find your code, find a small circle on the panel that shows a blinking light. Depending on the model it will blink fast then slow. For example, five fast, three slow is a code 53 which can be looked up and helpful when calling an HVAC company to come out.

It gives the technician a headstart on what’s going on. If you have an older furnace that doesn’t give you clear diagnostics, we’ve put up a list of common troubleshooting options to try.

Start Furnace Troubleshooting with Problems that are Easy

When furnace problems arise, you want to make sure that they are fixed as soon as possible. The furnace is usually the largest energy user in your home, so when it’s not working properly, your energy costs will go up exponentially.

You can quickly troubleshoot your furnace by checking:

  • Your system is turned on in heat mode.
  • The temperature is set correctly.
  • The breaker is flipped on and the fuse is working.
  • For a gas furnace, your pilot light may be out or there is something wrong with your gas line.
  • Your flame sensor may be dirty and may need to be cleaned.

Additional reading: How Long Does A Furnace Last & When To Replace It

Is there a Reset Button on a Furnace?

Resetting a furnace is an underappreciated skill among many homeowners, and it’s one that’s critical whether you have a gas or electric furnace. In many electric furnaces, a red or yellow reset button is usually inside the blower housing next to the blower motor located near the top of the furnace.

If you can’t easily find the reset button or your owner’s manual for help, the best option is to turn off the circuit breaker that controls it, then restart power to the furnace by turning the breaker back on. The furnace should start automatically and you should warm up quickly.

Resetting a Gas Furnace

Many gas furnace problems come from your filter or pilot light. Most newer furnaces have an automatic ignition that makes it easy to relight a pilot flame or does away with the pilot light altogether. 

If you have an older gas furnace that does have a pilot light check to see if the pilot light is out. If it is then refer to your owner’s manual on how to relight it, making sure that you don’t smell any gas in the area.

If you do smell gas, call the gas company immediately and leave the area. If your furnace is newer, a simple circuit breaker reset for your gas furnace should do the trick.

Why Does the Furnace Click But Not Turn On?

The furnace may have an insufficient power supply which means the furnace is not receiving enough voltage from the circuit breaker. It could also be faulty thermostat settings. To resolve these issues, try resetting the furnace by turning off the circuit breaker for 20 minutes then turning it back on again.

It could also be an electronic ignition problem. When the thermostat calls for heat, a gas furnace opens the gas valve, and once the sensor recognizes there is gas flowing it will ignite it which can have a clicking noise (like a gas stove).

If the flame is burning ineffectively it can make clicking noises as it works to start. It might also indicate a dirty or faulty flame sensor not telling the gas valve to open causing the ignitor to click uselessly. 

Other causes could be: 

  • A broken fan
  • Faulty electric furnace heating elements

Why Is My Furnace Making Strange Noises?

Any kind of strange noises coming from your furnace that can’t be easily identified or fixed with a reset could be the sign of something more problematic.

If the furnace is making whining, straining, or squealing sounds, it will still run but will stop eventually and you could find yourself buying a new furnace or heat pump. The main culprit is probably a slipped or frayed blower belt that needs an expert to fix. 

Don’t ignore strange noises coming from your furnace. If resetting the furnace doesn’t fix the problem it is time to call in a pro.

If the sounds seem to come from areas away from your furnace check for loose pipes or wires in attic space or crawlspace. Also, check for corrosion on metal parts such as pipes or gas lines. It could be a straightforward solution or your furnace telling you that it is time for maintenance.

Additional reading: How Much Does it Cost to Replace a Furnace?

Why Isn’t My Furnace Heating?

Another common furnace issue is the improper sizing of your heating system. It seems counterintuitive but furnaces that are too big for their homes create far more energy than is required.

This happens frequently, resulting in the thermostat turning off the furnace before it has had a chance to complete a full heating cycle. Furnaces of all sizes are intended to operate in cycles, with each producing a set quantity of output over a set length of time.

If your furnace cannot complete a full heating cycle it will not heat your home efficiently, cycling on and off frequently. 

A clogged furnace filter can indirectly cause your furnace to short cycle making it harder for your furnace to keep your home warm. Some furnaces have dual filters so remember to check and replace or clean them all.

Additional reading: The Best Temperature to Set Your Thermostat to in Winter

Why Do I Have High Energy Bills?

A dirty air filter is a clogged filter and that makes your furnace work harder. Left unchanged, a dirty air filter can cause high energy bills and damage your furnace, shortening its lifespan.

A dirty furnace filter makes it hard for the fan to circulate air, increasing the amount of power it needs to do its job and creating higher energy bills. Check your furnace air filter regularly – every one to two months in the heating season – to keep your energy bills low and indoor air quality high.

A too-small furnace will not be able to produce enough heat to keep the home warm, so it will run for longer than it was designed to in order to make up for it, creating higher energy bills.

This is essentially the same problem as if the system were too large, but with the same outcomes — more wear and tear on the equipment, resulting in a shorter furnace lifespan and higher operating costs.

Additional reading: Breathing Easier: Tips for Improving Indoor Air Quality

Why Is My Thermostat Blank?

There are a couple of reasons for your thermostat being blank. The first thing to consider is the thermostat batteries. If you suspect they are dead, change them and see if that is the issue. It also might need to be replaced. Thermostats typically have a lifespan of 10 years.

In high-efficiency condensing furnaces, if the thermostat is blank it’s usually the pump as it’s tied into the thermostat. Some furnaces have a safety switch that can be triggered when the unit becomes too hot or has an issue. You should have your furnace inspected immediately.

Read next: Why Your Old Thermostat is Probably Ready to Be Replaced

How Jacobs Can Help

HVAC systems are an investment that you want to make the most of – for your comfort and your wallet. When it comes to your HVAC system, you want a company that has the experience and knowledge to help you make informed decisions. Jacobs Heating & Air Conditioning experts are here to guide you. Jacobs consultants will help troubleshoot problems to ensure you have a long-lasting furnace system that will keep you comfortable all winter long.

By scheduling routine tune-ups with our technicians before any issues arise, they can identify potential problems early on so they don’t have time or cause major damage later down the road. We offer maintenance plans designed for homeowners to keep your gas or electric furnace running without the hassle of downtime and cold. No matter what you need we’re always just a phone call away. You are welcome to review our statement on COVID-19 and how we’re taking precautions to protect you, our team, and our communities.

About the Author

Amanda Jacobs portrait

Amanda Jacobs, Internal Project Manager

Amanda Jacobs is an Internal Projects Manager and 3rd generation member of Jacobs Heating & Air Conditioning. She received her MBA from Seattle University and has worked for a leading HVAC training and consulting firm. When not talking HVAC on the Jacobs Blog, you can find her on the golf course or whipping up her famous vegan chili.