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The shift from brisk autumn weather to the deep chill of a Midwestern winter can happen fast across the Metro East, South St. Louis, and Jefferson County. Your furnace or heat pump is your home’s shield against the cold, and when it fails, it’s more than just an inconvenience—it’s a threat to your comfort and safety. At Heritage Heating & Cooling, we live by our motto: “We’re not comfortable unless you are.” With nearly 15 years of dedicated experience as a family-owned and veteran-operated business, we’ve handled tens of thousands of heating and cooling issues. While a few problems are simple fixes, knowing the critical signs that demand a call to our licensed, insured, and background-checked HVAC technicians is essential to prevent a small issue from becoming a costly, dangerous emergency.
Critical Safety Issues: Turn it Off and Call Us
Some furnace issues are non-negotiable safety hazards that require immediate, professional attention. If you notice any of these signs, shut down your system and call for emergency service immediately.
The Smell of Gas or Rotten Eggs
Natural gas is treated with a chemical that gives it a distinct, pungent rotten egg smell. This is a clear indicator of a gas leak. Do not operate any electrical switches, light sources, or even your furnace itself. Leave the premises and call the gas company or emergency services first, followed by our emergency HVAC team at (618) 356-2781.
Your Carbon Monoxide Alarm is Triggered
Carbon monoxide (CO) is a deadly, odorless, and colorless gas. If your CO detector goes off, it is often a sign of a dangerously compromised furnace, typically a cracked heat exchanger. This is a life-threatening situation. Evacuate the property immediately and call for help. Our technicians are EPA certified and trained to diagnose and safely resolve these critical malfunctions.
Yellow or Flickering Pilot Light
For gas furnaces, the pilot light should burn with a steady, blue flame. A weak, yellow, or dancing flame indicates incomplete combustion, which can generate carbon monoxide and reduce efficiency. If you spot this, turn the furnace off; this requires a trained professional to inspect the burner assembly and ensure safe operation.
Performance Warning Signs: Beyond DIY Fixes
Once you've checked the easy things—like ensuring your thermostat is set to "Heat," the air filter is clean, and the circuit breaker hasn't tripped—these are the mechanical and performance issues that indicate a complex internal problem.
Strange or Excessive Noises
Your furnace should run quietly. Any new or louder noises—such as banging, screeching, rattling, or grinding—are warnings. Banging can signal igniter issues or dirty burners, while a screeching sound often means a worn-out blower motor bearing or belt. These mechanical failures can lead to total system failure if not addressed quickly by an expert who can repair all makes and models.
Constant Short-Cycling
When your furnace turns on for a short time, fails to heat the home sufficiently, and then shuts off repeatedly, it’s called short-cycling. This is inefficient, stressful on components, and often points to a serious issue like a faulty flame sensor, an overheating unit due to a blocked flue, or a furnace that is incorrectly sized for your home. Since we offer free estimates on new equipment, we can help you determine the root cause and the best solution.
Inconsistent or Lukewarm Airflow
If the fan is running but the air coming through the vents is not warm, the system is failing to generate heat. This could be due to a problem with the ignition system, gas supply, or a major component like the heat exchanger. Since we offer a one-year labor and parts warranty on our repairs, you can trust our highly trained team to diagnose the precise internal failure and fix it right the first time.
A Reliable Partner for Your Comfort
Don't let a major repair catch you off guard. If your furnace is over 15 years old, requires frequent repairs, or if the cost of a single repair exceeds 50% of the cost of a new system, our experts can provide a personalized consultation. As a family-owned business, we’re dedicated to delivering superior, personalized solutions and will help you explore all options, including our 0% financing for up to 60 months on new equipment.
For both residential and commercial HVAC services in O'Fallon and the wider Metro East, trust the experienced, insured, and bonded technicians at Heritage Heating & Cooling. We are available for same-day, weekend, and after-hours emergency services. Give us a call at (618) 356-2781 and rest assured your comfort is in excellent, professional hands.