Common Furnace Problems and How to Troubleshoot Them

Woman sitting by her heater on the phone, trying to troubleshoot why it won't turn on

When cold weather sets in, you rely on a well-functioning furnace to keep your home comfortable. However, like any mechanical system, a furnace can experience issues that disrupt its performance. If you’re noticing signs that your heating system isn’t working quite as it should, understanding some of the most common furnace problems can help you determine the right course of action.

From malfunctioning thermostats to a pilot light that just won’t stay on, the following insights will shed light on frequent issues with furnace heating and guide you through troubleshooting techniques. However, when the problems are too complex or too unsafe to handle on your own, Stay Cool Comfort Control is standing by to provide O’Fallon, MO, homeowners like you with reliable furnace repair and furnace installation when it’s the best course of action to take. We even offer regular furnace maintenance to prevent problems from popping up in the first place. 

Common Problems With Furnace Heating Systems

Furnaces have many interconnected parts, which means that when something goes wrong, it could be due to any number of components. Understanding the symptoms of these issues can help you identify and address them quickly. From small malfunctions to significant mechanical failures, the following list breaks down the most typical reasons a furnace stops working. Recognizing these signs can help you stay ahead of potential breakdowns.

  • Pilot Light Won’t Stay Lit – Essential for gas furnaces, the pilot light ignites the burners. When it doesn’t stay lit, it’s likely due to drafts, a dirty pilot opening, or issues with the thermocouple.
  • Malfunctioning Thermostat – The thermostat is crucial for regulating the furnace. When it fails, you might experience temperature inconsistencies or find that the furnace doesn’t start at all.
  • Clogged Furnace Filter – A dirty air filter restricts airflow, forcing the furnace to work harder and often resulting in overheating. This common issue can lead to shutdowns and even damage other parts over time.
  • Blower Motor Issues – The blower motor distributes warm air throughout your home. If it malfunctions or becomes obstructed, you might notice reduced airflow or no airflow at all.
  • Gas Valve Problems – The gas valve controls the flow of gas to the furnace. If it’s not functioning correctly, the furnace won’t receive enough fuel to heat your home effectively.
  • Flame Sensor Problems – The flame sensor detects whether the burners are lit. A dirty or damaged sensor can cause the furnace to shut down, as it may fail to sense the flame and signal for the gas to stop flowing.
  • Broken Heat Exchanger – Responsible for heating the air that circulates through your home, the heat exchanger is one of the most vital parts of a furnace. Cracks in this component can cause dangerous gas leaks.
  • Tripped Circuit Breaker – Furnaces use significant power, and a tripped circuit breaker can cut off electricity to the unit, leaving it non-operational until the breaker is reset.
  • Low or No Gas Supply – Gas furnaces rely on a steady supply of gas to produce heat. Disruptions in this supply, whether due to line issues or other obstructions, can leave your furnace unable to heat your home effectively.

Furnace Troubleshooting Guide

Knowing how to troubleshoot furnaces can save you from unnecessary repair costs and downtime. Here are steps to address each common issue in your heating system.

Thermostat Troubles

Malfunctioning thermostats can cause a host of issues. Start by checking the thermostat’s power source and replacing batteries if necessary. Gently clean the interior with a soft brush to remove any dust or debris that might interfere with its operation.

Next, verify that the settings are correct for the season. Sometimes, an accidental switch from “heat” to “cool” can be the culprit. Finally, test the thermostat by adjusting the temperature and listening for the furnace to kick on. If you’ve gone through these steps and your thermostat still seems unresponsive, it might be time for a replacement.

Dirty Filters and Blower Motor Problems

Poor airflow often stems from a dirty filter or a malfunctioning blower motor. For clogged filter issues, locate the filter housing, typically at the return air duct or blower compartment. If it’s visibly dirty, replace it with a new one of the same size and type. Remember to mark your calendar for monthly filter checks to prevent future problems.

When the furnace blower motor isn’t circulating warm air effectively, it may require a bit more investigation. Start by accessing the blower compartment and inspect the motor and fan blades. Clear away dust or debris that may have been collected on the components. If the motor sounds like it’s struggling or if you notice any unusual noises, the motor may be nearing the end of its lifespan.

Pilot Lights and Ignition Systems

Ignition problems can vary depending on whether your furnace uses a pilot light or an electronic ignition system. For pilot lights, locate the assembly and check if the flame is lit or if there are any drafts near the furnace. Sometimes, even a light breeze can extinguish the pilot flame. If drafts are not an issue, the thermocouple may be malfunctioning. This small device detects the flame and signals the furnace to keep supplying gas. A faulty thermocouple won’t hold the pilot flame, and it may need cleaning or replacement.

For those with electric ignition systems, you need to pay attention to the sounds your unit is making. When you turn on your furnace, listen for clicking noises. The ignitor might be defective if you hear clicking but don’t detect any heat. Unfortunately, diagnosing and repairing electronic ignition issues requires professional assistance due to the complex nature of these systems, so call your local HVAC technician today.

Circuit Breakers

Electrical issues can cause your furnace to shut down unexpectedly. If your furnace suddenly stops working, check your home’s electrical panel. Look for a tripped breaker in the “off” position. Reset it by pushing it fully to “off” and then back to “on.” If the breaker trips again, it could indicate a more serious electrical problem.

Flame Sensors

Another electrical component to consider is the flame sensor. This safety device can become coated with soot over time, causing your furnace to shut off prematurely. To address this, turn off the power to the furnace and contact a professional at Stay Cool Climate Control.

When to Reach Out to a Furnace Repair Technician

Sometimes, a furnace problem is bigger than what you can safely and effectively handle on your own. Even with the most in-depth online tutorials, there are certain issues that should only be addressed by a professional to preserve the life of your furnace and the well-being of your family. Here are some of the situations where expert intervention is non-negotiable:

Gas Line Concerns

If you have a gas furnace and believe the supply line could be the culprit of your heating dilemma, here is what you should do. With extreme caution, locate the valve near your furnace’s natural gas line connection and verify it is in the “on” position. However, if you smell gas at any point during this process, exit your home immediately and call your gas company. Do not attempt to manipulate the valve or any other components if you suspect a gas leak.

Heat Exchanger Issues

Heat exchanger issues are equally serious. Look for visible cracks or corrosion on the heat exchanger, and listen for rattling sounds when the blower runs. If you suspect a cracked heat exchanger, shut off your furnace immediately and call a professional. This component plays a crucial role in preventing carbon monoxide from entering your living space, so prompt attention is vital.

Repeated Pilot Light Problems

Once you have carefully and precisely followed the manufacturer’s guidelines for relighting or have conducted tests and heard clicking without heat being produced, the thermocouple likely needs to be replaced. Also, you should never try to work with the pilot light if you are unsure or uncomfortable. Calling a technician to do the job will give you peace of mind that the matter will be dealt with in a safe and accurate manner.

Stay Warm & Safe With Preventative Furnace Maintenance

The performance and longevity of all HVAC systems, including furnaces, hinges on the level and frequency of the care they receive. While you can and should perform simple upkeep tasks like changing your furnace’s filter every couple of months and keeping the area around the unit free from debris, a thorough inspection and tune-up can only be achieved by an HVAC professional, like those at Stay Cool Climate Control.

During these regularly scheduled visits, our crew performs a range of actions that are essential for optimal furnace performance. These include checking the ignition system, cleaning blower components, lubricating moving parts, and inspecting the heat exchanger for cracks or wear.

While these service agreements might seem like an unnecessary expense, think about the money you will save on premature replacement and corrective repairs. Moreover, consider the safety and well-being of your family and how routine furnace maintenance can help catch potential dangers before they lead to devastating consequences.

Furnace Frustrations? Call for Answers & Resolutions to All Your Burning Questions

At Stay Cool Climate Control, our priority is your comfort. Whether you need assistance with furnace repair, regular maintenance, or replacement, our qualified specialists are here to help. We’ll keep your furnace running smoothly so you can focus on enjoying a warm, comfortable home all winter long. Call today to book an appointment!

=== SE Button Script ===
Scroll to Top