Possible Causes of Air Conditioner Knocking Noise and Recommended Fixing Options

The air conditioner has become an essential part of most homes in this modern age. It helps to retain a comfortable indoor temperature during warm days. Advanced technology has made the recent ACs generate low to zero noise. That’s why if you hear an air conditioner knocking noise from your unit, it is worth looking into the problem carefully.

Why Is My Air Conditioner Making A Knocking Noise?

Possible reasons can compel strange noises made by home equipment. Not all of them require help from professionals, especially the common ones. Discover some of the most common causes of why your AC makes a knocking sound below and what is recommended to do to resolve the issue.

air conditioner knocking noise

Fan problems

If the fan’s metal blades are damaged or bent because of age, misalignment, bad installation, or debris, they may clash with the AC’s frame resulting in loud knocking noises.

Failing blower or fan motor

Do you know that a damaged blower motor, fan motor, or aging bearings can cause knocking noise or banging sound? The unusual sounds from the system may show up as the result of the faulty compressor.

Faulty or loose compressor components

In most cases, a knocking sound is produced by the condenser outdoor AC unit. It signals that the piston pin, support screws or springs, or the crankshaft are loose or malfunctioning. A loose condition may be due wear and tear. This problem may require you to replace the compressor or have a professional replace or fasten the loose components.

Dirty Filter

The next possible reason why your AC unit creates a knocking sound is because of a clogged filter. If you don’t clean the filters regularly, a blockage may happen due to accumulating dirt and debris, which causes the blower engine to strain and generate the knocking noise. Make sure that you clean and change the filter for maximum air conditioning performance.

Stuck debris in the outdoor air conditioning unit

External objects like dirt, dust, leaves, or twigs have the potential to interrupt the outdoor unit. These things may land within the unit, resulting in knocking or rattling sounds. If it’s ignored, this problem can cause heavy damage to the system. Contact a professional to perform thorough cleaning and to look for possible further damage.

Air Conditioner Making Knocking Noise When Off

In another scenario, you may wonder why my air conditioner makes a banging sound when it turns off? This problem can be caused by the reasons listed above, but they are only parts of the possible causes.

You should know that any strange or loud noise produced by the air conditioning is worth your concern. It is usually the earliest sign of broken components that have a chance of requiring immediate action. Try to find out the source of the problem to find the solution as soon as possible after hearing the unusual sounds.

In some cases, DIY repair is sufficient to bring back the AC system to normal. There are also plenty of scenarios where you will need a professional to inspect, detect, and fix the issue. Major issues usually are linked to an electrical problem that can exhibit danger if you are unqualified to tackle the situation by yourself.

On the other hand, if your air conditioning unit has been working for a long and nearing the end of its expected lifespan, it is worth considering a replacement. Catching the right cause of why you hear an air conditioner knocking noise can help prevent further unwanted troubles.

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AirconMag is an experienced author and Air Conditioner expert. With years of practical experience in the field authored several informative articles on various aspects of AC unit, including installation, maintenance, and repair