Reasons Why Your Furnace is Making Noise

December 27, 2023

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Hearing your furnace make noise can be unnerving. You may not know what is going on or why it’s making the racket. There are many reasons your furnace could be making noise. You can fix some of these things yourself, while others will require a professional to service the unit. Let’s look at some familiar sources of noise and what they mean for your home comfort system.


If your furnace is moving parts around, you might hear an unusual noise. The most important source of sound when it comes to furnaces is the blower motor. The blower blows air into the system so that heat can radiate through the home more efficiently and also makes sure that no cold air gets sent back into the living area.

If you hear banging or grinding when the furnace turns on, that is usually an indication that something in the blower assembly has become loose. This is not likely to cause significant damage to the system, but it may render it less efficient than usual.


If your furnace is making noise, it’s also possible that the lubrication system isn’t working correctly. A lack of oil in the blower assembly can cause it to go out of balance and vibrate while operating. This will typically create a whirring or rattling sound when you turn on the unit. If there is very little oil in the system, or if there is a leak in the lubrication line, an oil change may be all that’s needed to fix this problem.

At first, it can be challenging to see exactly where problems with lubrication are occurring. You will need to examine your unit from the inside and locate any apparent signs of leakage. In some cases, oil drips onto the blower motor, which causes damage that can be heard. Your unit may not be lubricated enough for regular operation, but this is less likely than a leaky line. If you notice oil mixing with dust or debris in your unit, it’s probably time for an oil change.


Your furnace may also be making noise if the air filters are clogged. To keep your system running efficiently, it’s important to replace filters every three months or so during peak heating and cooling seasons. This is especially important if you have pets in the home that frequently shed, as their fur can become lodged in the vents and restrict airflow.

If you hear rattling inside the unit, think about how air filters might affect that sound. If you remove your filter and hear a distinct change in the noise, your filter most likely needs to be replaced. Be sure to check all filters in your unit for clogs before attempting any repairs on the system itself.


There are several reasons why your furnace might not be able to blow enough air through the system. Blowers typically require a certain amount of static pressure to operate correctly, and if there is not enough, this can cause problems. A lack of static pressure can come from poor insulation in the home or blocked ventilation ducts. If you’ve noticed difficulty heating the house when the furnace is running, this could be a problem.

If you can’t create enough static pressure with the existing blower, you will need a new forced air system in your home to repair it. This may mean adding more vents and ductwork in some cases. These repairs are best left up to a professional HVAC technician who can address any severe airflow problems with the home. You can reach out to Alberta Mountain Air Heating and Air Conditioning in Calgary if your furnace has airflow problems.


Your furnace blower fan is one of the essential parts of your HVAC system because it pushes air through your home. The fan will need to be repaired or replaced if you hear any unusual sounds coming from it while operating. Because the blower motor has moving parts, it will become less efficient at pushing air through the system over time. Several signs indicate your blower fan is in bad shape, including sporadic rattling or grinding sounds when the unit turns on.

There may be a problem with the motor bearings if you can’t locate an obvious sign of damage to the blower assembly itself. This part of the unit is built to run smoothly and quietly, and if it produces grinding or rattling noises, it is wearing out. You will want to replace this motor if that happens.


Your furnace’s condenser runs outside on an exterior wall and sometimes produces strange noises while operating. If you hear what sounds like water trickling or dripping inside your home, this is usually an indication that the condenser fan motor has gone wrong. Condensers can also make buzzing noises in colder weather due to condensed moisture building upon the unit’s coils.

If you hear rattling sounds coming from your condenser, then it could be that there are gaps in the insulation around the unit. Your condenser needs to be protected adequately to run efficiently, and if the coils are exposed to extreme cold, it can cause problems with noise production.


Another common issue that causes weird noises in a furnace is electrical damage. The blower motor itself will have wires running from it to the system’s control board, and if those become damaged, you’ll be able to hear unusual sounds from the unit. The same can be said for any other components in your furnace, including the fan motor and the heating coils.

Your furnace has a large amount of wiring that can be difficult to repair, and you should let a professional handle this type of work. If the wires become damaged or disconnected, then your home will not receive enough power to produce heat adequately, and may also lead to strange noises in the unit when it tries to begin heating. In some cases, it can even lead to electrical fires.


The most obvious sign that your furnace needs repair is an inconsistent heat output from the unit. If you notice that one area of your home or a specific room is always colder than others, this could be a problem with the airflow in the house. It can also be a problem with the system’s wiring or controls, which will need to be inspected and repaired if there is any evidence of damage to them.


Inspect your furnace for any physical obstacles that may be clogging the system during operation. This can include large amounts of pet hair, dirt, or other debris accumulated in spaces around the unit’s vents. When you turn on the furnace, it will automatically try to push air through these devices, but if they are clogged, the air will not move through the system properly. If you notice that your home is dusty or unusually dirty, it may be time for professional cleaning of all vents in your home. This can help ensure that your furnace is operating effectively and smoothly.

Your furnace could be producing noise because of many reasons, as explained above. If your furnace makes strange noises, schedule an appointment with Alberta Mountain Air Heating and Air Conditioning. We will send our technicians to inspect your furnace, and they will recommend the best course of action. If you have any other heating and air conditioning problems in your home, do not hesitate to reach us. We can assist you with heating and cooling repair, installation and maintenance.

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