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7 Super Common Furnace Repairs and Problems You Should Know About

10 Super Common Furnace Repairs and Problems You Should Know About

10 Super Common Furnace Repairs and Problems You Should Know About

Despite our long summer, winter appears to have arrived in a hurry. Suddenly the furnace is your favorite appliance in the house. When problems arise, you know it right away. Keeping your home warm is a combination of regular maintenance and knowing the symptoms of a furnace problem. You can start today by educating yourself about the most common furnace repairs and problems, as well as how to spot them.

Table of Contents

What Are the Most Common Furnace Problems?

Whether you’re a first-time homeowner or you’re running a business at a brick-and-mortar store, you’re likely to run into at least a few problems with your furnace over the years.

The most common problems with furnaces are:

  1. Dirty ductwork
  2. Old filters
  3. Faulty starting mechanism
  4. Broken blower components
  5. Malfunctioning heat exchanger
  6. Bad Limit Switch
  7. Thermostat in need of repair
  8. Tripped circuit breaker
  9. Unexpected noises
  10. Gas leaks or odors

Let’s take a closer look at each of these common furnace problems individually.

Cleaning Dirty Ductwork

Dusting Vents for Furnace Repair

As simple as this repair may seem, it's an important one everyone needs to know about. Every once in a while, dust and debris can get into your heating ducts. That limits the amount of hot air you receive.

If you've noticed that your furnace doesn't seem to be heating the house as well as it once did, your ductwork could use a cleaning session. You can check the airflow by placing your hand in front of your vents and feeling the amount of air that is coming out.

To prevent future problems, you should get on a regular maintenance plan with an HVAC technician you trust. We'll be able to clean out your ductwork and the rest of your HVAC system so keep your heat up and running.

Changing Filters

Your furnace has a filter that keeps your air clean and keeps your ductwork cleaner as well. Your filter blocks dirt, allergens, pollutants, and other hitchhikers in the air.

While most homeowners know about furnace filters, they don't know how often to change their filters. It depends on the filter itself, but you should replace most filters every month or two. Check your filter's packaging for a more specific timeline.

A key sign that you need to replace your filter is that your furnace may not heat the air as well as expected. If your furnace seems to be working harder than it should be, that could signal a filter change too. This happens because the filter is full and the furnace is struggling to get air through it.

Fixing the Starting Mechanism

Each furnace has a mechanism to jumpstart the heating cycle. The type of mechanism depends on the furnace itself.

In older furnaces, this is usually a pilot light. Newer furnaces typically use electrical ignitions instead of pilot lights.

Regardless of your furnace, the ignition or the pilot light can fail and we may need to replace it or repair it. In some cases, your furnace may stop turning on and heating the home when your ignition or pilot light has a problem.

You may be able to see the pilot light inside the furnace. Regardless, though, if your furnace isn't turning on when it should, it's worth a call to an HVAC technician.

Fixing Blower Components

Dirty Blower for Furnace Repair

Your furnace has a blower mechanism, which blows the heated air into the ducts so it warms your home.

If you’ve noticed your furnace isn’t blowing hot air anymore, there could be a few problems that need fixing.

Replacing Blower Bearings

One part of that blower mechanism that can fail is the set of ball bearings.

Over time, ball bearings can develop wear and tear. They can also sustain damage if they're installed incorrectly.

The key sign of a problem with your blower bearings is a scraping sound coming from your furnace. If you hear this sound, contact an HVAC repair specialist right away so we can replace your bearings.

Keep in mind that as you continue running your furnace, you'll damage the bearings further. It's a good idea to turn off your furnace to prevent the problem from getting worse.

Replacing Blower Belt

We mentioned earlier that your furnace uses a blower to push the heated air into your home. The ball bearings are far from the only part of that blower that can break.

One common issue is a problem with the belt for your blower fan. You'll know this is happening when you hear a high-pitched squeal from the furnace.

There are multiple things that can go wrong with your blower belt. The belt can slip out of place, and an HVAC technician may only need to put it back in place.

In other cases, your blower belt suffers from wear and tear over time and will eventually break. If that happens, we will likely need to replace the belt.

Either of these problems can make your furnace less efficient. You won't get the heat you need but you'll also be paying a high energy bill for your inefficient furnace.

Damaged Blower Capacitor

The capacitor is the true powerhouse that gets the blower motor working. It works like a battery, releasing amps of energy to power the system.

If the capacitor is damaged, the motor ends up utilizing the circuit board for all energy requirements. This causes a surge in power. It could trip the breaker or even cause a short circuit.

A furnace that starts working but stops midway often has a damaged blower capacitor. Fortunately, an HVAC professional can inspect the damage and conclude whether a replacement is required.

Replacing the Heat Exchanger

You probably haven't heard of it before, but trust us: you're grateful for your furnace's heat exchanger.

The heat exchanger is a coil of heated tubes. Your furnace pushes air through these heated tubes to warm the air before pushing that warm air into your home. In other words, this is where all the heat comes from in your furnace.

With the amount of heat those tubes handle, though, you need to keep up with regular furnace maintenance to keep them in good shape. If you don't, they can crack or have other malfunctions.

When this happens, our technicians will most likely need to replace your heat exchanger. This is one of the more expensive repairs you could need, but it's less expensive than buying a new furnace.

If you notice that you're letting air out of your vents but it isn't very warm, the heat exchanger may be the problem.

Fixing the Limit Switch

The limit switch is a part of your furnace that not only makes sure the furnace is running well, but it keeps you safe too.

A limit switch detects the heat within the furnace. Responding to that temperature, it tells the blower fan when to turn on and off.

On top of this, the limit switch can tell when your furnace is getting dangerously hot. It will shut off the furnace's burners to prevent potential fires, severe furnace damage, and other important dangers.

One of the most common signs that your limit switch is malfunctioning is that your furnace will keep running continuously when it shouldn't. While this might not seem serious at the time, it can leave you vulnerable to dangerous problems because the limit switch won't turn off an overheating furnace.

In this case, call an HVAC technician to either repair or replace the limit switch.

Cleaning the Flame Sensor

The high limit switch has a flame sensor rod positioned on its surface. The minute your furnace starts, it is the flame sensor’s job to inspect the presence of a flame. If no pilot flame is detected, the sensor will trigger safety features to shut down the system.

When the flame sensor malfunctions, the furnace stops running a cycle. The problem usually lies in the maintenance of the sensor. Over time, soot, debris, and other byproducts accumulate over the sensor rod. This hampers its working, causing delays in sensing the flame and abruptly shutting the system.

If the damage is not far-fetched, you can clean the flame sensor by unscrewing it from the access panel. If it appears to be a complicated process, let our HVAC professionals handle it. The technician will also determine whether there is a need for replacement.

Repairing Your Thermostat

Furnace Thermostat Repair

In some cases, the problem with your furnace isn't a problem with the furnace at all.

Your thermostat detects the temperature in your home. Based on that, it tells the furnace when to start a heating cycle.

A malfunctioning thermostat could pick up the wrong temperature. This leads your furnace to either produce heat you don't need or to stop producing heat when your room is cold.

Your thermostat may also have a problem with the messages it sends to the furnace. The electrical system can have issues at any time.

An HVAC technician will be able to examine your thermostat and determine if there is an issue with the software or the hardware. We'll be able to either get your thermostat back up and running or replace it with a functioning one.

Tripped Circuit Breaker

A furnace may trip the circuit breaker due to a temporary power surge. If resetting the breaker gets the system in order, you are good to go. However, continual tripping is a matter of concern.

Perhaps, you use a shared circuit to power your furnace and some other heavy electrical appliance. Otherwise, ground faults within the circuitry could have also caused an influx of energy.

Regardless, you will have to look into electrical maintenance and repair. Try powering the furnace as an isolated unit or separating its circuit board.

Unexpected Noises

One of the most noticeable signs of problems with your furnace is a series of unpleasant noises. These can range from clunking to thumping to squealing and more.

As we mentioned above, a squeaking noise often mans a blower belt problem. A scraping noise tends to signal damage to your blower bearings. A clunking noise, on the other hand, has more possibilities.

Furnaces are full of various mechanical parts that could break or become loose at any time. In these cases, the only way to track down the problem is for a specialized technician to take a look. To make sure you aren't at risk for a fire or further damage, try to turn off your furnace until your service call.


Gas Leaks or Odors

You can expect a slight burning smell from the furnace if you turn it on at the beginning of the season. Over time, layers of dust accumulate in the system and burn off as it heats up. This smell should only occur once or twice and disperse within an hour.

Otherwise, smells from the furnace are something you should be concerned about. A moldy smell indicates the growth of allergens and debris.

If you can sense gas, or a metallic smell, take immediate action. Turn off your gas valve and open all windows and doors in the house. Call for an immediate furnace repair and, if possible, evacuate the house in the meantime.

How Do You Troubleshoot a Furnace Problem?

Diagnosing the root problem in a furnace is not very straightforward. Even if you have a thorough understanding of the common issues with a furnace, you must identify one culprit.

In a furnace system, each component gets to perform an equally important function. Additional factors such as surrounding temperature, cleanliness, and energy supply are also partly responsible. In this scenario, pinpointing a singular reason can be a daunting job.

Before calling on furnace repairs, you can do a bit of troubleshooting on your own. This will help you cancel out common furnace problems that do not necessarily involve extensive servicing.

Begin from the energy supply reaching the furnace, as it is the component upon which everything else depends.

Electricity Supply

Check the power switch directly connected to the furnace. Perhaps, you forgot to turn it on.

Next, head to your main circuit breaker panel. Check if the HVAC switch is working. The switch can trip due to high voltage, so turn it back on if it’s tripped. Wait to see whether this reset prevents it from tripping again.

Gas Supply

If no fuel reaches the furnace, the ignitor won’t be able to heat the gas to warm up the air. Check the main gas valve located outside the house. The switch should be resting parallel to the gas line to work.

Double-check the supply by turning on some other gas appliance. If it doesn't work, your furnace isn’t at fault here. Instead, the issue lies in the gas connection, and a local gas supplier can help resolve it.

Other Culprits

Furnace systems are programmed to shut down when the environmental conditions are not optimal. Therefore, you should next examine the external factors contributing to its working properly.

  • Thermostat. For the furnace to run, you should set your thermostat to HEAT rather than COLD. Adjust the temperature 5-10 degrees higher than that of the surroundings to see if the furnace kicks on. If you have a programmable system, check for an error code in the date or time. Reset the system according to the required conditions.
  • Drain Pan. All HVAC systems utilize the drain pan to dispense away the collected water. The pans can overflow with water or get clogged with debris due to lack of maintenance. This can trigger the safety switches in the system, causing the ignition to shut off.
  • Air Filter. A dirty air filter is the worst companion for a furnace. It will restrict the airflow from reaching the blower chamber. Therefore, there will be delays or complete blockage in the ignition. Replace the dirty filter and get a filter-check light installed by an HVAC technician. This will help you regularly check up on the filter health.
  • Access Panel. A safety switch in the furnace will not allow the blower fan to work if the furnace door is open. Thus, assure that the access panel is firmly in place.

Why Is My Furnace Running But There’s No Heat?

A furnace will begin running when it receives sufficient energy to power the blower motor. However, it will heat the air only when the ignition has started.

A furnace ignitor is responsible for this process. It creates a spark, converting the gas supply into heat. Therefore, the air coming out of the furnace becomes heated. When the ignitor fails to create the spark, the furnace gives out the same cold air blowing in the surroundings.

Perform a troubleshooting process to ensure that the thermostat and the gas valve are properly functioning. If all else is fine, look for other warning signs of a failed ignitor.

Call a heating and cooling company to handle the situation and replace the faulty ignitor. If dealt with at its initial stages, the replacement is an inexpensive and hassle-free procedure. Leaving the problem unchecked could worsen the damage and lead to more significant furnace repairs.

Identifying the Common Furnace Repairs Your Home Needs

Furnace Repair

When there's a nip in the air outside, your home should be a warm and welcoming place of comfort. A malfunctioning furnace can take away that comfort in a hurry.

By learning about the common furnace repairs above, you can know what to look for and narrow down what may be wrong with your furnace.

You can also recognize the importance of an ongoing furnace maintenance program during the warm months and cold months alike.

Keep in mind that the information above is a mere guideline.

The only way to know for sure what is causing problems with your furnace is to call an HVAC technician to examine it with a trained eye.

We can help you prevent serious problems or even safety risks by resolving your furnace problems quickly.

If your furnace needs some TLC, call our HVAC technicians for service.

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