Thwapping, Banging, And Squealingl: 3 Problematic Sounds You Don't Want Your HVAC Unit To Make

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Your heating and cooling system is a complex part of your home's value and family's comfort. Since you will use your heating and air conditioning all through the year, problems are likely to occur. Considering that half of your home's total energy usage goes towards heating and cooling, ensuring that your system is in good working condition is smart for energy conservation and financial savings. If your outdoor units make one or more of these common noises, you may have an issue that requires immediate repair.


While not an actual word, thwapping is an excellent way to describe the sound your blower makes when an object is stuck between the blades.

The thwapping sound may be similar to the shuffling of a deck of cards, but an object stuck in between the blower's blades is not a game. If the object is left in between the blades, the blower will most likely wear down. This worn blower will cause your unit to struggle with proper heating and cooling, which may increase energy usage and your monthly bills.

Shut off your system and disconnect the power before removing the unit's exterior casing. Locate and remove the item stuck in between the blades.


If you hear a loud banging sound coming from your outdoor units while the system is running, shut off the power immediately. The banging may stem from an issue inside the blower assembly.

In most cases, the banging will be due to a part that has become loose or disconnected from the blower motor. A heating and air technician will need to inspect the blower motor and assembly to determine which part has disconnected.


A periodic thwapping and banging from your outdoor units is common, but a squealing sound may signify a more involved issue. If your units make a squealing sound while running, there may be a mechanical issue affecting the compressor or air handler.

Your HVAC technician will first inspect the compressor's motor. Squealing may occur if the compressor's motor lacks sufficient lubrication. In addition, you may hear the sound if the motor's bearings are worn down or loose.

If the squealing sound is more prominent inside your home instead of outside from the unit, there is an issue with the system's air handler. The blower motor of the air handler may be dirty or not functioning properly. Also, your technician may need to replace damaged bearings or fan blades.

For more information, contact Elite Heating, Cooling and Plumbing or a similar company.