Why Is My AC So Loud?

Few air conditioners offer truly whisper-quiet performance. Even when brand new, many AC units make slight humming sounds during operation or faint clicking noises when first starting up. However, if your AC is grinding, shrieking, hissing, or downright disruptive, there’s likely an underlying problem. The following are 10 possible reasons why the AC in your Wheat Ridge, CO, home is ultra-loud.

1. Age-Related Wear

Like all heating and cooling equipment, air conditioners become increasingly noisy as they age. Whether due to loose or worn components, build-ups of debris, or greater temperature-related expansion and contraction, age-related noises aren’t always possible to mitigate with maintenance or troubleshooting.

If your air conditioner is 15 years old or older and becoming increasingly loud, your best bet may be to swap it out for an upgraded model. With many ACs losing nearly half of their efficiency after just one decade of service, swapping an old air conditioner for a new and more efficient one could lead to both quieter operation and a noticeable decrease in your home energy bills.

2. Your HVAC Air Filter Is Dirty or Improperly Sized

AC air filters are among the first components to check when troubleshooting loud sounds. All the air that enters the system must pass through them. If your HVAC air filter is improperly sized or oriented, you might hear rhythmic clanging or slamming sounds coming from your indoor air handler. Each time the air pressure within your AC system changes or your blower fan starts or stops moving, an undersized air filter will rattle around.

Dirty air filters inhibit airflow. This makes air conditioners work harder. You might hear your air conditioner humming or whirring loudly, or you might hear your outdoor condenser unit buzzing. These are both indications that the indoor evaporator coil is frozen or freezing due to built-up debris. Putting a fresh air filter in and having your AC tuned up should solve the problem.

3. There Are Airflow Obstructions in Other Areas

It’s also important to check your HVAC air vents and your outdoor condenser unit for obstructions. Your AC condenser should have at least 24 inches of clearance on all sides. If it does not, hot refrigerant could have a hard time releasing its heat, and pressure will mount. Blocked AC condensers often make high-pitched squealing or hissing sounds until obstructions are cleared.

4. Loose Parts

Rattling or clanging sounds could indicate loose parts. Often, when these noises are rhythmic, one or more components are barely attached. When rattling sounds become louder and more erratic, this may mean that a loose part has come completely off and is banging into other features. To prevent additional damage, turn your AC off and schedule service right away.

5. Worn Electrical Contracts or Other Electrical Issues

Buzzing sounds are a sign of worn electrical contacts, damaged circuits, or other electrical troubles. Among the most common electrical problems in air conditioners and heat pumps are failed or failing capacitors.

Air conditioners require more electricity at start-up than residential electrical systems can supply. They also have high electricity demands during their cooling cycles. Capacitors make up for this deficiency by drawing and storing power during air conditioners’ downtime. If either component malfunctions or fails, you’ll hear a low buzzing sound as your AC struggles to get moving and stay that way.

6. Broken or Bent Fan Blades

Buzzing might also mean that one or more of your air conditioner’s fan blades are bent or stuck. This might be the result of fast-moving debris such as pebbles, twigs, or larger rocks. Sometimes small insects and animals find their way into AC condensers and cause fan blade damage. Running an AC with jammed fan blades will eventually cause the blower motor to overheat or burn out.

When fan blades are only minimally bent and can still move, you might hear rattling or knocking sounds as they bang into housing walls. This friction causes undue wear and contributes to poor AC performance. During annual air conditioner maintenance, we inspect and test fan blades. We also lubricate all moving parts to limit friction and promote quiet operation.

7. Dirty, Damaged Ducting, or Ductwork Infestations

Do you ever hear scratching or scurrying sounds when turning your AC on? This is a likely sign that your ducts are infested with rodents or other small pests. HVAC air ducts are a primary target for pests. They make excellent transit highways, and they provide secure, private shelter.

When pests enter and inhabit air ducts, indoor air quality rapidly declines. Buildups of feces and food create pungent indoor odors and may lead to increased humidity. To resolve the problem, have your ductwork inspected, sealed, and professionally cleaned. If your pest problem has spread to other areas or home systems, you’ll need to treat them too.

8. Your AC Has a Refrigerant Leak

AC compressors act as the heart of air conditioners by pressurizing refrigerant and pumping it from end to end and back again. Unfortunately, high pressure and constant temperature changes can lead to loose connections and worn tubing over time. If your AC compressor ever starts hissing, buzzing, bubbling, or short cycling, you might have a refrigerant leak.

As refrigerant seeps out, AC compressors struggle to keep their remaining fluid pressurized. If this problem is left unchecked and homeowners continue to run their cooling systems, AC compressors could collapse or permanently shut down. Only licensed HVAC companies should diagnose and repair refrigerant problems.

9. Your AC Compressor Is Failing

Your air conditioner’s compressor is easily its most costly component. While air conditioners come with limited parts warranties, AC compressors are protected by manufacturer warranties for up to 10 years.

Bubbling and hissing may indicate a refrigerant leak, but refrigerant leaks are hardly the only problem that compressors can experience. Loud rumbling and rattling sounds may mean that your AC compressor has reached the end of its lifespan. Although some air conditioners can last as long as 20 years, ACs that are used heavily or installed in high-humidity or low-IAQ homes may break down much sooner. If your AC compressor vibrates and rumbles whenever your cooling system cycles on, this could be the case. Frequent problems with overheating due to dirty air filters or insufficient professional maintenance can cause AC compressors to fail prematurely as well. Unprotected power surges that lead to overheating also take a major toll on these appliances.

10. The AC Fan Belt Is Loose or Misaligned

Light squeaking, squealing, or thumping noises are often due to loose or misaligned fan belts. During annual AC maintenance, we check the integrity and alignment of fan belts and adjust as needed. If you haven’t scheduled annual maintenance in a while, this is a likely cause of any excessive outdoor AC noise.

We help homeowners in Wheat Ridge keep their air conditioners in top condition. We offer top-notch heating, cooling, and electrical services. We also provide new water heaters and cutting-edge indoor air quality improvements. If your AC is making strange sounds, contact Mighty Pine Heating & Air today to schedule an appointment.