Skip navigation

Why Your Furnace Is Making That Weird Noise

BurnerThere are a lot of different signs and symptoms that can indicate a furnace is in trouble. Odd noises are one of the most common warning signs, and are often among the first homeowners tend to notice. If your furnace is making some kind of noise it doesn’t normally make, there might be a problem with it that requires professional repair. Have a look at some of the more common noises below that indicate a problem.


The furnace is able to circulate air throughout the home by using a part called the air handler. This is a part made up of a motor and a large fan. The air handler motor has a lot of strain put on it during operation, so it uses oiled bearings to keep itself running smoothly. These bearings do a good enough job at keeping the air handler running, but they don’t last forever. Over time, the bearings wear down and the friction on the air handler increases. Eventually, the friction becomes significant enough that the air handler starts to make a loud grinding sound while the furnace is running. If you hear this sound, you should call for repairs as soon as possible. If the bearings are not replaced in time, the air handler motor will burn out and need to be replaced. That will be significantly more expensive, so time is of the essence.

Short Cycling

Short cycling is when the furnace turns itself on and off every couple of minutes, instead of completing a full heating cycle. This is often caused by electrical issues, though a clogged air filter or malfunctioning air handler can also lead to it happening. The short term effects of short cycling are that the system is unable to properly heat the home. That’s not the only problem caused by short cycling, though. The longer the furnace is allowed to short cycle, the more rapidly it wears out. Short cycling makes it more likely for problems to occur with the furnace, and also shortens its lifespan significantly. If you notice your furnace short cycling, you need to call for repairs as soon as you can.


If your gas furnace makes a loud boom every time it turns on, you probably have an issue with delayed ignition. Delayed ignition is the result of carbon particles building up on the burner assembly over time, causing the jets to take longer and longer to ignite. When a delayed jet finally does ignite, it burns through a lot of gas at once and creates that loud boom. The way to prevent this is to have a professional technician clean out your assembly every once in a while. If you have this problem, however, you should act quickly. Eventually, the jets in the assembly can become so clogged that they will actually fail to ignite at all.

Comfy Heating & Air Conditioning Inc. offers furnace repairs of all kinds in Fremont, CA. If you need to have your furnace repaired, contact us today to schedule an appointment.

Comments are closed.