Air Conditioner Noises To Be Aware Of

Air conditioners are not completely quiet. Even new systems will make some sounds. These noises are from the system’s normal operations and are not a cause for concern. However, an air conditioner making noise can also point to a more significant issue. In these cases, a professional HVAC technician should inspect your unit immediately because these unusual noises can point to a part or parts not working properly. This results in the air conditioning system not functioning as it should.

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Air Conditioner Noises To Watch Out For

Modern air conditioning units are quieter than older ones. HVAC technology has led to many models equipped with noise-dampening technology and variable-speed compressors, ensuring air conditioners generate 55 dB or less noise. This noise level is the same level of noise that an average dishwasher emits. If the air conditioner has a problem, it will likely create sounds like the following:

AC Unit Is Buzzing

image of outdoor air conditioning unit in summer

An air conditioner that’s buzzing may have an electrical problem. Another cause is loose or unbalanced fan blades in the outdoor condenser unit. The buzzing sounds can also be due to a damaged outdoor fan motor, other loose components, and dirty condenser coils. An AC with a refrigerant leak also emits a distinct buzzing sound.

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Humming Coming From A/C System

A humming air conditioner may point to a damaged contactor relay switch. The air conditioner has difficulty switching on when this component gets damaged since the thermostat signals the contactor relay switch to start up the condenser. This is an electrical issue that should only be handled by a licensed HVAC technician. In some cases, fan motor problems can also produce humming noises.

Clicking Air Conditioner


It can be confusing when you hear clicking noises because they may sound like the noise an air conditioner makes during the start or end of a cooling cycle. However, frequent or constant clicking may point to a thermostat problem. If this is the case, you may require a thermostat replacement. Make sure that a licensed HVAC technician performs this task.

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Air Conditioning Screeching Sound

One of the most distinct sounds a defective air conditioner makes is “screeching”. This issue points to a malfunctioning fan motor in the condenser unit. This fan is responsible for eliminating the heat from the refrigerant. A damaged fan means the air conditioner cannot lower indoor temperatures. 

Screeching sounds may also point to a damaged blower fan motor. Blower fans help eliminate heat and humidity inside your home, forcing the air to the return ductwork where the AC system cools it. The blower fan will circulate the cooled air throughout the house using the vents.

Other likely reasons the air conditioner produces screeching sounds are a faulty fan belt and damaged fan motor bearings. Call your HVAC contractor immediately if your air conditioning unit makes loud squeals or screeches.

A/C Unit Whistling

image of an hvac contractor checking ac refrigerant levels

Another symptom to look out for is a high-pitched or whistling noise making your air conditioner sound like it is screaming. This noise is typically caused by a coolant leak or high pressure within the compressor. Both problems are severe and should only be handled by a professional immediately. If this issue occurs, switch off the system and contact a trusted HVAC technician. 

Air Conditioner Clanking

If your air conditioner system sounds like it has a loose metal part hitting another, you likely need to replace a component. You will also hear clanking sounds if there are loose or unbalanced parts. For instance, the outdoor fan or indoor blower may have gotten loose or unstable, hitting other parts. This causes the clanking sound. Call an HVAC technician immediately if your air conditioner is clanking or rattling. Don’t wait for it to worsen because metal hitting metal can only cause further damage and expensive repairs.

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Cooling System Is Banging

A damaged compressor is likely the reason banging noises in your AC occur. These noises are common in older units. The air conditioner’s components may have gotten loose or unfastened from regular wear and tear and age. It can also be that a part of the air conditioner is broken, like the crankshaft, piston pin, or connecting rod. An imbalanced indoor blower may also cause banging noises. If you hear a banging noise, you will likely require an AC compressor replacement.

Whirring Noise From Your AC

You may have a mechanical issue if it sounds like your air conditioner has a drone or a helicopter inside it. Some causes may include a defective blower fan motor, a faulty fan belt, and a malfunctioning fan. A loose fan blade can also cause whirring noises. The best-case scenario is that the outdoor or indoor blower fan has trapped debris, causing the problem. If you know how a piece of paper sounds when it hits a fan, consider this sound as a warning. 

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Rattling Coming From Air Conditioner

air conditioner condenser with overgrown plants

A rattling noise coming from your outdoor air conditioning unit can be caused by loose debris in the condenser. Dirt, twigs, and leaves may have dropped inside the unit. This is easy to fix as it only requires opening the outdoor unit to remove the debris. If you have a clean unit, the noises may be due to an AC electrical contractor issue. Repair this right away to prevent the damage from getting worse.

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Air conditioners should last you around 15 years or more if they pass the manufacturer’s quality test, are installed correctly, maintained regularly, and used reasonably. However, time will eventually catch up, and it may not work how it used to. Never assume it is a simple problem if you are unsure what to do. Contact your local HVAC technician to determine the issue properly and apply the right solutions. 

Call Lake Region Energy For All Of Your HVAC Requirements

Lake Region Energy offers exceptional HVAC services in southwestern Maine. We hire the best professionally certified technicians to provide you with high-quality heating and cooling replacements, installations, tune-ups, and repairs. Each of our friendly techs has the experience, knowledge, and skills to service your HVAC system correctly.

Our company offers the area’s most competitive HVAC service costs. Our maintenance services can help increase energy efficiency and comfort while reducing heating and cooling expenses. If you need an HVAC repair or replacement system, we can recommend the best home solution while staying within your budget. We back all our work with a guarantee because your satisfaction is our priority. Schedule a service appointment with Lake Region Energy today. We provide free, in-home estimates.

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For more information about our fuel deliveries and HVAC services, be sure to contact Lake Region Energy. You can click here to contact us, or you can call us at (207) 839-5500 to find out more. We offer a full line of heating and cooling repairs, maintenance services, and installations.

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