Testing your furnace in the fall can help you identify potential problems that may impact your heating once frigid temperatures arrive. For example, after months of no use, your system could start producing loud noises you can hear throughout your home. If your furnace is well-maintained, you should only hear the system clicking on, followed by a soft whooshing. Other sounds like banging, squealing, or popping could point to serious internal issues. When testing your heating system, listen for these key warning signs that may indicate you need furnace repair services.

Booming and Banging

Hearing a sudden loud noise when you first turn on your furnace often points to delayed ignition. In a healthy HVAC system, your thermostat will send a signal to your furnace to produce heat when the temperature in your home goes below where you have set it. The gas valves open, the burners ignite, and the heating cycle starts. Unfortunately, due to issues like grime buildup or compromised parts, there may be a delay before the burners ignite. During the delay, gas accumulates until the burners finally fire up. This will create a small but audible explosion. While this sounds like a significant hazard, it doesn’t put your household in immediate danger. It’s still best to call in an expert soon before this issue starts causing damage to other components.

Popping and Clicking

Older furnaces are known to emit small popping or clicking noises occasionally. This sound comes from your metal ductwork expanding from the hot air being distributed around your home. However, these noises could also point to problems like dirty furnace burners or cracked heat exchangers. Other signs that these components may be the issue besides noises include changes in the pilot light color, foul odors, and cool air coming from your vents. You can deal with burner dirt buildup by scheduling maintenance. On the other hand, you should address any issues concerning your heat exchanger immediately because any damage to this component can lead to harmful carbon monoxide leaks.


A constant rattling may point to loose belts or disconnected metal panels within the furnace cabinet. This issue is often caused by regular wear and tear over the years. It’s not a high-risk sound unless it’s related to your blower motor belt. Only an expert technician can accurately diagnose the problem and provide the necessary repair service or part replacements.

Squealing and Whistling

Sharp squealing or scraping can mean the system is struggling with malfunctioning blower motor bearings. These bearings surround the shaft of the motor, allowing it to run fast without being slowed down by friction. They can become compromised due to old age, lack of lubrication, or grime buildup. You should address this issue sooner rather than later because it may cause your furnace blower motor to overheat. Whistling, on the other hand, is often related to obstructions within your vents, ductwork, or filters.


A bird-like chirping noise is a more uncommon sound, but it can occasionally happen when your furnace is heating up before the start of a cycle. In some cases, unfortunately, it could also mean the blower motor is out of alignment. Some of the surrounding metal may even be out of place and touching the blower wheel, creating a faint chirping or squeaking. If the sound doesn’t go away immediately after the furnace starts up, it is probably time to schedule furnace repair services.

The Importance of Timely Repairs

Using your furnace for months every year causes significant wear and tear on its components. As these parts begin to slide out of place or fail, they can create a host of noises. The longer the issues causing these sounds are ignored, the further the damage can spread. Rather than risk an expensive emergency breakdown, contacting a HVAC professional at the first sign of trouble is the smart decision.

Local Quality Heating Services

At El Indio AC, we excel at delivering the best residential HVAC services in Tolleson, AZ. We guarantee your complete satisfaction whether you need a new system installation or a quick tune-up. Our team also offers convenient 24/7 emergency repair so that you never have to worry about going without heating. Count on us for all your HVAC maintenance and replacements. We also provide ductwork and home automation services. Contact El Indio AC today to schedule an appointment with one of our expert technicians.

company icon