Common Causes and Solutions for a Loud AC

Few things disrupt a peaceful afternoon or a restful night’s sleep as quickly as a loud air conditioner. Whether it’s a bothersome hissing, screeching, or squealing sound, these disruptions not only disturb your tranquility but also serve as red flags for underlying issues with your air conditioning system. HVAC.com provides insights into the most common loud AC noises, their potential meanings, and solutions to resolve them.

Loud Air Conditioner Noises and Their Meaning

Hissing

An AC hissing noise may sound like a snake, but in reality, it indicates a serious problem with your air conditioner’s refrigerant system. Refrigerant leaks produce a hissing sound due to the high-pressure release of gas escaping through a very small opening. Refrigerants can be potentially dangerous and should only be handled by a certified HVAC contractor who has the training and know-how to diagnose and recharge it. A refrigerant leak can lead to inefficient operation or complete failure of your AC, as it results in the loss of essential coolant used in the air conditioning process.

Banging or Clanking

Loud banging or clanking noises typically indicate a loose or broken part within the air conditioning compressor or the indoor air handling unit. It’s crucial to contact a qualified HVAC contractor at the first sign of these noises to prevent further damage. They will inspect the system and make the necessary repairs, which might include tightening or replacing certain components.

Clicking

You may hear a light clicking sound when the air conditioner turns on and off. However, persistent or irregular clicking may indicate a more serious problem, including electrical issues or malfunctioning components within the air conditioning system, which require professional inspection and repair. Issues with the fan unit or thermostat can also potentially cause an AC clicking sound.

Rattling

One of the most frequent causes of an air conditioner rattling sound is debris – such as sticks, leaves, and pebbles – becoming trapped in the AC condenser unit. An HVAC contractor can remove all of the debris to prevent further damage and restore your air conditioner to proper working condition. Other reasons your AC may be rattling include loose screws or bolts and loose ductwork. Loose air ducts can cause a rattling sound when the air passing through them creates vibrations that are amplified when the ducts are not securely fastened.

Squealing

Squealing is another noise that indicates a problem with your air conditioner. 

An AC squealing noise is usually caused by a worn-out fan belt or malfunctioning motor bearings. An HVAC technician can tighten or replace the belt or lubricate or replace the bearings, respectively.

Grinding

An AC grinding noise is also indicative of issues with the system’s motor bearings, requiring lubrication or replacement.

Buzzing

Buzzing is another frequent AC noise that should be promptly inspected. One common cause of AC buzzing noises is the presence of a loose or broken part, which could involve an electrical component or the condenser fan blade. A frozen air conditioner or a malfunctioning compressor can also cause buzzing noises.

Whooshing

An air conditioner whooshing sound resembles a rushing or blowing noise. Common causes of AC whooshing include a clogged air filter that restricts airflow, leaks in the ductwork, blocked vents, blower fan issues, and a damaged fan motor. Contact a reputable HVAC company to inspect the air conditioner and the ductwork to isolate the problem and make the appropriate repairs.

Whistling or Whirring

If you notice a whistling or whirring noise coming from your AC, it could signal potential concerns with the fan blades or motor, such as debris obstruction or misalignment, which may require cleaning or adjustment to restore optimal functionality. Addressing these noises promptly can help prevent further damage and ensure your AC operates efficiently.

Prevent a Loud AC By Identifying Underlying Issues

To prevent the likelihood of issues arising that lead to a loud air conditioner, it’s crucial to have professional air conditioner maintenance performed annually, preferably in the spring when it’s recommended.

During an AC maintenance tune-up, an HVAC technician can spot potential concerns, preventing them from escalating into loud noises and costly repairs. You can also prevent loud air conditioner noises by performing DIY tasks such as changing the air filter regularly and removing debris around the outdoor AC condenser to prevent potential concerns.