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The latest energy-efficient central air conditioning systems feature two-stage or variable speed motors that are engineered to produce little to no noise. If you notice a loud and disruptive sound from your air conditioner, this is a clear indicator of a moderate to severe issue. These noises are often a sign it’s time to repair or replace your unit. To help you diagnose the issue with your system, these are the 8 most common air conditioner noises that you should not ignore.

Why Is My Air Conditioning (AC) Unit Making Loud Noises?

Banging Noises

If your air conditioner is making a banging noise, this is an indicator of a problem with the compressor. This component is engineered to distribute refrigerant to various parts of the HVAC system to remove excess heat from your home. As your central air conditioning (AC) unit reaches the middle or end of its lifespan, it is not uncommon for parts to become loose inside the compressor.

Once the parts become unfastened in the compressor, you may notice a rattling noise while your air conditioning system is activated. This sound is caused by detached components that are hitting the compressor’s exterior framing. Since the compressor is not engineered to be easily disassembled, you may be required to invest in a new energy-efficient air conditioner. If your air conditioner is producing a banging sound, call a local HVAC technician in your area to receive assistance with this problem.

Screeching Sounds

The most common issue associated with an air conditioner screeching noise is a malfunctioning fan motor in the outdoor condenser unit. The central air conditioning system connected to your home features a fan that is designed to remove heat from the refrigerant.

If your air conditioner is making a shrieking noise, this is an indicator of an issue with the fan motor. This sound may also be caused by a broken motor in the compressor of the condenser system. A screeching or squealing noise may also be caused by a damaged blower fan motor inside your house. The blower fan is engineered to collect warm air from each room of your home.

Once the blower fan motor is activated, the hot and humid air throughout your enclosure will be collected by your return ducts and sent to your air conditioning system. Next, the cold air from your system will be distributed throughout your house by the blower fan. 

You may also notice a screeching sound near the HVAC system in your house due to damaged bearings in your fan motor. In addition, an impaired fan belt may also be the root cause of this noise. If you hear a loud AC sound, immediately turn off your air conditioner and call a professional HVAC contractor. 

Humming Noises

You may begin to notice a loud humming noise inside your air conditioner (AC) unit due to a defective contactor relay switch. This component is designed to start the outdoor condenser unit when it receives a signal from your thermostat.

Unfortunately, you will not be able to turn on your air conditioner until this issue is inspected and fixed by a licensed technician. Do not ignore electrical issues in your system. This will cause severe damage to your central air conditioning system that will be accompanied by expensive repairs.

Buzzing Sounds

Never ignore a buzzing noise from your central air conditioning system. This sound may signal loose or unbalanced fan blades in your outdoor condenser unit. This type of sound may also be caused by issues such as a faulty outdoor fan motor, dirty condenser coils, and loose components.

A buzzing sound may also be a sign of an obstruction near the copper lines that are connected to your air conditioner. The most severe issue that may be the culprit of this problem is a refrigerant leak. Please do not ignore a buzzing sound. Be proactive and prepare for the summer season by hiring a licensed technician to perform an air conditioner tune-up.

Rattling Noises

In a best case scenario, your air conditioner may be making a rattling noise due to loose sticks, dirt, or leaves in your outdoor condenser unit. The easiest way to fix this issue is to disassemble the unit to remove these items.

In a worst case scenario, this air conditioner sound may be produced by a damaged electrical contractor in your system. If you notice a malfunctioning contractor, this issue should be fixed as soon as possible to prevent damage to the compressor of your central air conditioner.

Clicking Sounds

While it may be normal to hear a clicking noise at the beginning or end of your cooling cycles, it is not normal to hear a continuous clicking sound from your air conditioner. This type of sound may be an indicator of a malfunctioning thermostat. Since the process of removing and installing a new thermostat is not easy, call a licensed contractor in your neighborhood to receive help.

Hissing Noises

If your air conditioner is making a hissing noise, this may be a signal of a moderate to severe air duct leak in your house. This sound may also be the product of a malfunctioning expansion valve or an air filter that is not compatible with your system. Immediately call a professional to perform an inspection of your air conditioning system.

Bubbling Sounds

The air conditioner connected to your house may be making a bubbling noise due to excess moisture. This type of problem may be produced by a blockage, crack, or hole in your drainage pipe. If you are a handy individual, it is easy to disassemble your air conditioner to inspect the drainage line.

On the other hand, we do not recommend replacing the drainage line on your own. To fix the bubbling sound in your air conditioner, you will need special tools, equipment, skills, and training. Please call a certified technician to ensure the job is completed correctly and safely.

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