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Your Furnace is Not Working? Here Are 5 Common Problems and How to Fix Them


A man checking them thermostat

October is finally here and as the crispness of fall fills the air, it serves as a timely reminder that the heating season is here. Amidst the excitement of all things pumpkin-spiced, it's crucial to ensure your home's heating system, particularly the furnace, is primed for the impending colder months. Just like any mechanical system, furnaces can occasionally encounter hiccups that leave you feeling less than cozy. But fret not! In this comprehensive guide, we'll delve into typical furnace issues and provide practical solutions to guarantee your home remains a haven of warmth throughout fall and winter.

#1: Furnace Problem: The Ignition System

Problem: Pilot Light Outages

A pilot light is a small flame responsible for igniting the fuel that heats your home. When the pilot light goes out, the furnace ceases to operate. Several factors can contribute to a pilot light outage. A common culprit is a dirty or clogged pilot orifice—the small hole where the pilot light burns. If this orifice becomes obstructed, the pilot light can't remain lit. Another potential issue is a malfunctioning thermocouple—a sensor that communicates the pilot light's status to the furnace. A faulty thermocouple can prevent the furnace from recognizing that the pilot light is lit, resulting in a failure to turn on.

To rectify a pilot light outage, the pilot orifice and/or the thermocouple may need cleaning or replacement. Although these tasks can often be carried out following the instructions in your furnace's owner's manual, if uncertainty or discomfort arises, seeking professional assistance is wise to ensure safety.

#2: Poor or Uneven Airflow

Problem: Clogged Filters

Are you experiencing uneven heating, with one room feeling like an icebox while another exudes toasty warmth? This common issue often stems from airflow irregularities. Dirty or clogged filters can restrict the flow of air through the furnace, resulting in decreased efficiency and potential damage.

Filters can become clogged for various reasons. A primary factor is neglecting regular filter changes—filters should ideally be replaced every 1-3 months, depending on their type. Another cause of clogged filters is using the wrong size or type for your furnace.

Preventing filter-related problems involves consistent filter changes and ensuring the correct size and type are used. By doing so, you'll maintain optimal airflow, contributing to efficient and effective heating.

Dirty or clogged filters can restrict the flow of air through the furnace, resulting in decreased efficiency and potential damage.

#3: Unusual Noises, Weak Circulation, or Cycling On and Off

A hand over a furnace vent

Problem: Blower Motor Issues

The blower motor is responsible for circulating air through your furnace and home. When the blower motor malfunctions, your furnace's ability to heat your living spaces effectively can be compromised.

Numerous factors can contribute to blower motor issues. One common cause is a dirty or clogged blower wheel—the component that propels the air. If the wheel is obstructed, the blower motor can't circulate air efficiently. Another potential culprit is a faulty capacitor—a small device aiding in the blower motor's startup. If the capacitor is faulty, the blower motor might struggle to initiate or operate at the correct speed.

Addressing blower motor problems may involve cleaning or replacing the blower wheel and/or capacitor. Given the intricacies involved, seeking the expertise of a qualified professional is often the best approach to ensure proper repair.

#4: Unusual Odors, Flame Rollouts, and Flickering Yellow Pilot Lights

Problem: Heat Exchanger Issues

The heat exchanger plays a pivotal role in transferring heat from the combustion process to the circulated air within your home. A damaged heat exchanger can potentially release harmful gases into your living spaces, posing serious risks.

Heat exchanger issues can arise due to various factors. Corrosion is a common cause—moisture or chemicals in the air can contribute to its development over time. Another potential issue is cracks in the heat exchanger, often stemming from manufacturing defects or physical damage.

Should the heat exchanger become damaged, repairing or replacing it is imperative. However, this task should only be undertaken by a qualified technician to ensure the safety and proper functioning of your furnace.

#5: Temperamental Thermostats

Problem: Thermostat Issues

The thermostat serves as the command center for your home's temperature control. When the thermostat malfunctions, your furnace might struggle to maintain the desired temperature, impacting your comfort.

Several factors can lead to thermostat problems. One common cause is a dirty or corroded thermostat, which can affect accuracy and responsiveness. Regular cleaning is essential to prevent these issues. Another potential culprit is a faulty thermostat—replacement might be necessary if internal components are compromised.

To ward off thermostat issues, regular cleaning and prompt replacement when necessary are recommended. By maintaining a well-functioning thermostat, you'll enjoy consistent and comfortable temperatures.


As you prepare for the upcoming seasons, ensuring your furnace's optimal performance is paramount. Recognizing and addressing common furnace problems promptly empowers you to maintain a cozy and energy-efficient home environment. While some troubleshooting can be handled independently, remember that safety takes precedence, and complex repairs or replacements are best left to qualified professionals. By staying proactive, you'll ensure that your heating system operates seamlessly, offering warmth and comfort as you savor fall's delights in the welcoming embrace of your home.

For professional assistance with any of these furnace problems or for furnace maintenance, repairs, or replacement, our dedicated team at Express Plumbing and Heating is here to support you. With our expertise, your comfort remains our top priority.



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