5 Warning Signs Your Furnace Is About to Break Down

How to Spot Problems Early and Avoid a Heating Emergency

Few things are more frustrating than waking up on a freezing winter morning to find that your furnace has stopped working. A furnace breakdown is not just inconvenient; it can also lead to costly emergency repairs or even a full system replacement.


The good news is that most furnaces give off warning signs before they completely fail. By recognizing these signs early, you can avoid sudden breakdowns, stay warm all winter, and save money on repairs. If you notice any of the following five warning signs, it’s time to call a professional HVAC technician for an inspection before a minor issue turns into a major problem.



1. Your Furnace is Blowing Cold Air

If your furnace is running, but your home still feels chilly, something is definitely wrong. Furnaces should consistently provide warm air when needed.


Possible Causes of Cold Air from Your Furnace:

  • Dirty air filters blocking proper airflow
  • Pilot light or ignition system failure
  • Thermostat malfunctions preventing proper heating
  • Ductwork leaks allowing warm air to escape


Before assuming the worst, check your thermostat settings and replace your air filter. If the problem persists, your furnace may need professional attention to diagnose and fix the issue.


2. Strange Noises Coming from Your Furnace

Your furnace should operate quietly in the background. If you start hearing banging, rattling, squealing, or grinding noises, it’s a clear sign that something is wrong.


Common Furnace Noises and What They Mean:

  • Banging or booming – This could indicate a delayed ignition or dirty burners, which can be dangerous.
  • Squealing or screeching – Often caused by a worn-out belt or motor bearings that need lubrication.
  • Rattling or vibrating – Loose panels or internal components may be the issue.
  • Clicking sounds – A faulty ignition system or a malfunctioning gas valve could be the cause.


Ignoring these sounds can lead to serious damage or even a complete system failure. If you hear unusual noises, schedule an inspection with a heating professional as soon as possible.


3. Your Energy Bills Are Higher Than Usual

If your heating costs have suddenly spiked without a change in outdoor temperatures, your furnace may be struggling to operate efficiently.


Why Your Furnace is Driving Up Your Energy Bills:

  • Aging system – Older furnaces lose efficiency over time.
  • Clogged air filters – A dirty filter makes your furnace work harder, using more energy.
  • Leaky ductwork – Heated air escaping through cracks forces your system to run longer.
  • Failing components – A worn-out blower motor or malfunctioning thermostat can cause excessive energy consumption.


Higher energy bills are often the first warning sign that your furnace needs maintenance or a potential upgrade. Addressing the issue early can save you money in the long run.


4. Your Furnace is Short Cycling (Turning On and Off Frequently)

If your furnace turns on and off repeatedly without fully heating your home, this is known as short cycling. This behavior can lead to premature wear and tear on your system, reducing its lifespan.


Possible Causes of Short Cycling:

  • Overheating – A dirty filter or blocked airflow can cause the system to shut down to prevent damage.
  • Thermostat issues – A faulty thermostat may not be reading temperatures correctly.
  • Improper furnace sizing – If your furnace is too large for your home, it will heat up too quickly and shut off before completing a full cycle.


Short cycling increases energy costs and puts unnecessary stress on your furnace, leading to more frequent repairs. A professional HVAC inspection can identify and fix the underlying issue.


5. Unusual Smells or Poor Air Quality

A properly functioning furnace should not produce strange odors. If you notice burning, musty, or gas-like smells, it could indicate a serious problem.


Common Furnace Smells and Their Causes:

  • Burning smell – This can happen when dust burns off after the first use of the season, but if the smell persists, it could be a sign of electrical issues.
  • Musty odor – Moisture buildup or mold growth in your ductwork may be the culprit.
  • Gas smell (like rotten eggs) – This is an emergency situation. It could indicate a gas leak, and you should turn off your furnace immediately and call your gas company.


Additionally, if you notice more dust, dry air, or increased allergy symptoms, your furnace may not be filtering air properly. Replacing air filters regularly and scheduling professional maintenance can improve air quality.


When to Call ARCO Heating & Cooling for Furnace Repair


If you’re experiencing any of these warning signs, your furnace could be at risk of breaking down. The sooner you address the issue, the more likely you are to avoid costly emergency repairs or system failure.


Call a Professional If:

  • Your furnace is blowing cold air instead of heat
  • You hear unusual noises like banging, rattling, or squealing
  • Your energy bills have increased suddenly
  • Your furnace keeps turning on and off
  • You notice burning, musty, or gas-like odors


Regular furnace maintenance can extend the life of your system, improve efficiency, and prevent breakdowns. The best way to ensure your furnace is working properly is to schedule a professional inspection before winter is in full swing.


Schedule Your Furnace Inspection with ARCO Heating & Cooling Today

Don’t wait for a complete furnace breakdown before taking action. If you’ve noticed any of these warning signs, contact ARCO Heating & Cooling to schedule an inspection and get your heating system back on track.


Call Now to Schedule Your Furnace Maintenance

📞 (636) 259-3961


Stay warm, save money, and avoid unexpected furnace failures this winter with expert HVAC service from ARCO Heating & Cooling.

A mini split white air conditioner are sitting next to each other on a white background.
By ARCO HEATING AND COOLING June 3, 2025
Flexible Comfort for Every Room and Every Season Living in Missouri and Illinois means experiencing all four seasons—and sometimes all in the same week! From hot, humid summers to icy winters, homeowners need heating and cooling systems that can adapt to changing weather. That’s where mini-split systems shine. At Arco Heating & Cooling, we specialize in mini-split installations tailored to the unique needs of homes across the Midwest. What Is a Mini-Split System? A mini-split system is a type of ductless HVAC that provides targeted heating and cooling to individual rooms or zones in your home. Unlike central systems that push air through ducts, mini-splits use small, wall-mounted indoor units connected to an outdoor compressor. Benefits of Mini-Split Systems 1. Zoned Comfort Customize temperatures for different rooms or areas. No more fighting over the thermostat or wasting energy in unused spaces. 2. Energy Efficiency Mini-splits avoid the energy losses associated with ductwork, making them more efficient than traditional systems. Many models are ENERGY STAR® certified. 3. Year-Round Climate Control With both heating and cooling capabilities, mini-splits are perfect for Missouri and Illinois’ unpredictable weather patterns. 4. Easy Installation No ductwork? No problem. Mini-splits are ideal for older homes, additions, basements, and garages. 5. Quiet Operation Mini-splits are known for being whisper-quiet, making them a great option for bedrooms, nurseries, or home offices. Why Arco Heating & Cooling? We bring years of experience installing and servicing mini-split systems throughout Missouri and Illinois. Our technicians will: Recommend the best unit for your space and needs Provide professional, clean installation Help you understand how to use your system for maximum comfort and efficiency Get Ready for Comfort—No Matter the Season Don’t settle for uneven temperatures or high energy bills. Whether you're renovating or simply looking for more control over your indoor climate, mini-splits are a smart investment. As a trusted heating and cooling contractor based in St. Charles, MO , we proudly serve the entire St. Louis metropolitan area, including both Missouri and Illinois. Call ARCO Heating & Cooling today at (636) 389-6471 to schedule a consultation and discover how a mini-split system can transform your home's comfort!
A person is pressing a button on a thermostat that is set to 70 degrees
By ARCO HEATING AND COOLING May 22, 2025
Upgrade You r Comfort and Savings with Smart Thermostat Technology Your thermostat plays a much bigger role in your home’s energy efficiency than you might think. Whether you’re heating your home in the winter or cooling it in the summer, how and when your HVAC system runs often comes down to thermostat control. At Arco Heating & Cooling , we help homeowners boost efficiency with expert thermostat installation services —including the latest in smart thermostat technology. Why Thermostats Matter Your thermostat acts as the brain of your heating and cooling system. When it's outdated or inefficient, it can lead to: Inconsistent temperatures Increased energy use Higher monthly utility bills On the other hand, upgrading to a modern thermostat—especially a smart thermostat—can significantly improve your system’s performance. Benefits of Smart Thermostats 1. Energy Savings Smart thermostats learn your habits and adjust temperatures automatically for optimal efficiency, helping you save up to 10–15% on heating and cooling costs. 2. Remote Access Use your smartphone to control your home’s temperature from anywhere. This is especially useful for busy families, travelers, or anyone who forgets to adjust the thermostat before leaving. 3. Customized Scheduling Set detailed schedules for different times of day or days of the week to avoid wasting energy when no one’s home. 4. Energy Reports Many models provide insight into your energy use, showing where you can make adjustments to save even more. 5. Integration with Smart Home Systems Smart thermostats can connect to Alexa, Google Home, and other smart devices for full-home automation. Arco Heating & Cooling's Thermostat Installation Services We offer: Expert recommendations for the best smart thermostat to fit your HVAC system Professional installation to ensure correct setup and compatibility Guidance on app setup, programming, and usage Make the Smart Move Today Don't let an outdated thermostat cost you comfort and cash. Upgrade to a smart thermostat and take control of your energy use. As a trusted heating and cooling contractor based in St. Charles, MO , we proudly serve the entire St. Louis metropolitan area, including both Missouri and Illinois. Call ARCO Heating & Cooling today at (636) 389-6471 to schedule your thermostat installation and start saving energy the smart way!
A man with glasses is covering his nose in a living room. A bad smell.
By ARCO HEVAC May 2, 2025
Identifying HVAC Odors in Your Home—and When to Take Action Unusual smells in your home can be alarming—especially when they come from your heating and cooling system. Some odors are harmless, but others can signal serious issues. At Arco Heating & Cooling, we help homeowners identify HVAC-related smells and determine when it's time to worry—and take action. Common HVAC Smells and What They Mean 1. Burning Dust Smells like: Burning or dusty odor When it happens: Usually when turning on your heat for the first time in the season Should you worry? Not usually. It’s common and usually goes away quickly as dust burns off your heating elements. 2. Electrical or Burning Plastic Smell Smells like : Hot wires, melting plastic When it happens: While the system is running Should you worry? Yes. This may signal overheating parts, frayed wires, or a serious electrical issue. Turn off the system and call a professional immediately. 3. Rotten Egg or Sulfur Smell Smells like: Sulfur, rotten eggs When it happens: At any time Should you worry? Absolutely. This could indicate a natural gas leak. Leave your home immediately and contact your gas provider and HVAC technician. 4. Musty or Moldy Smell Smells like: Damp basement, mildew When it happens: Often when the AC runs Should you worry? Yes. This could be a sign of mold or mildew in your ducts or system. Not only can this affect indoor air quality, but it can also impact your family’s health. 5. Sewage or Dead Animal Smell Smells like: Foul, decaying odor When it happens: Sporadically or continuously Should you worry? Yes. You might have a pest problem or a sewage backup near your HVAC system. Call a professional to inspect it. What To Do If You Notice a Strange Smell Don’t ignore it . Even if the smell seems minor, it could be a warning sign. Turn off your system if the smell is electrical, smoky, or foul. Call a licensed HVAC professional like Arco Heating & Cooling to diagnose the issue safely and quickly. Trust Arco Heating & Cooling to Sniff Out the Problem Our team has the tools and experience to diagnose strange odors and fix HVAC issues fast. Whether it’s a routine cleaning, an electrical fix, or system replacement, we’re here to help keep your home safe and comfortable. As a trusted heating and cooling contractor based in St. Charles, MO , we proudly serve the entire St. Louis metropolitan area , including both Missouri and Illinois. Call ARCO Heating & Cooling today at (636) 389-6471 to schedule your inspection and get peace of mind!
A woman is sitting on a couch in a living room holding a HVAC remote control.
By ARCO HEATING AND COOLING April 25, 2025
How Seasonal Shifts Impact the Air You Breathe When spring turns into summer or fall shifts into winter, your home’s indoor air quality (IAQ) can change dramatically. These transitional seasons bring fluctuating temperatures, increased allergens, and different HVAC usage patterns—all of which can affect the health and comfort of your indoor environment. At Arco Heating & Cooling , we’re here to help you understand these shifts and keep your home’s air clean and comfortable year-round. What Happens to Indoor Air Quality in Transitional Seasons? More Time Indoors, More Exposure As temperatures become unpredictable, people tend to spend more time inside. While this keeps you comfortable, it also means you’re breathing indoor air more frequently—and if that air is filled with dust, pollen, or other irritants, it can take a toll on your health. Allergens Are on the Move Spring and fall are peak seasons for pollen, mold spores, and other allergens. Without proper filtration and ventilation, these particles can easily find their way indoors and linger in your HVAC system. HVAC Systems Kick Into Gear Transitional seasons often involve switching between heating and cooling. This inconsistent use of your HVAC system can lead to dust buildup in filters and ducts, impacting air quality and system efficiency. Signs of Poor Indoor Air Quality Persistent allergy symptoms Dust buildup near vents Musty or stale indoor smells Dry skin or throat irritation Excess humidity or dryness If you're experiencing any of these, it may be time to improve your indoor air quality. Arco Heating & Cooling’s Indoor Air Quality Solutions Tailored to Missouri and Illinois Homes We offer a range of products and services designed to enhance IAQ throughout transitional seasons: Air purifiers : Capture and remove airborne particles including pollen, dust, and bacteria. Humidifiers and dehumidifiers : Balance humidity levels to prevent mold growth and dry air discomfort. HEPA filters : High-efficiency filters for cleaner, healthier air. Duct cleaning services : Eliminate built-up dust, mold, and debris in your ductwork. Smart HVAC controls : Automate air quality monitoring and adjustments for convenience and efficiency. Our expert team will assess your needs and recommend the right solution to improve your indoor air all year long. Breathe Better This Season—and Every Season Your home should be a safe, comfortable place, no matter the weather outside. By investing in indoor air quality solutions, you protect your health, enhance comfort, and improve HVAC efficiency. Let Arco Heating & Cooling help you transition smoothly into every new season. As a trusted heating and cooling contractor based in St. Charles, MO , we proudly serve the entire St. Louis metropolitan area, including both Missouri and Illinois. Call ARCO Heating & Cooling today at (636) 389-6471 to schedule your indoor air quality consultation. Breathe easier with expert solutions tailored to your home.
A white air conditioner is hanging on a wall next to a window.
By ARCO HEATING AND COOLING April 25, 2025
Find the Perfect HVAC Fit for Your Home's Comfort and Efficiency Selecting the right HVAC system isn’t just about brand or features—it’s about choosing a unit that fits your home’s size and layout. An improperly sized system can lead to high energy bills, uneven temperatures, and unnecessary wear and tear. At Arco Heating & Cooling , we help you choose the perfect system for optimal performance and year-round comfort. Why HVAC System Size Matters An HVAC system that’s too large or too small can cause a variety of issues: Oversized systems short-cycle, leading to inefficient operation and uneven temperature control. Undersized systems run constantly, struggle to maintain comfort, and lead to higher energy usage and faster wear. Correct sizing ensures maximum efficiency, lower utility bills, and a longer-lasting system. Key Factors in HVAC Sizing 1. Square Footage of Your Home The size of your home is the most critical factor. HVAC systems are rated in BTUs (British Thermal Units), and each square foot of living space typically requires a certain number of BTUs. 2. Climate Zone Homes in colder or hotter climates require more powerful systems to maintain comfort. Missouri’s four-season weather means your HVAC system needs to handle both heating and cooling efficiently. 3. Home Layout and Insulation High ceilings, window placement, and insulation quality can impact your home’s heating and cooling needs. A well-insulated home may require a smaller unit than a drafty one. 4. Number of Occupants and Appliances More people and heat-generating appliances (like ovens) can affect your home's internal temperature and should be factored into system sizing. Let Arco Heating & Cooling Help Choosing the right HVAC system doesn't have to be a guessing game. Arco Heating & Cooling offers expert consultation services to: Evaluate your home’s size, layout, and needs. Recommend HVAC systems based on BTU requirements and efficiency ratings. Provide professional installation and ongoing maintenance for peak performance. Get the Right System, the First Time Don’t risk investing in the wrong HVAC setup. Let the experts at Arco Heating & Cooling guide you toward a system that fits your home, budget, and comfort goals perfectly. As a trusted heating and cooling contractor based in St. Charles, MO , we proudly serve the entire St. Louis metropolitan area , including both Missouri and Illinois. Call ARCO Heating & Cooling today at (636) 389-6471 to schedule your HVAC consultation and make the smart choice for your home!
A man is working on an air conditioner and pointing at the wires.
By Arco Heating and Cooling March 4, 2025
Keep Your Heating and Cooling System Running Smoothly Year-Round
Two men are working on a furnace in a basement.
By Arco Heating and Cooling March 4, 2025
Keep Your Home Warm & Cozy Without Unexpected HVAC Breakdowns 
A man is working on an air conditioner with a hose.
By Arco Heating and Cooling March 4, 2025
Stay Warm & Safe with These Essential Furnace Safety Tips 
It shows the amount of co2 in the air.
By Arco Heating and Cooling March 4, 2025
Protect Your Home & Family from the Dangers of Carbon Monoxide 
A man wearing red gloves is working on a boiler.
By Arco Heating and Cooling March 4, 2025
Save Money & Stay Warm with the Best Heating Options 
Show More