Why is my air conditioner so loud?



Living without an air conditioner (A/C) can be a nuisance, especially during the hot summer months. Air conditioners are prone to breaking down and can become noisy and inefficient over time. A perfectly working A/C shouldn’t make more noise than a quiet hum. 

If yours is rattling, squeaking, squealing or making other strange noises, the unit could have a problem. Noisy air conditioners are a pesky issue for homeowners and business owners who operate A/C units. This article will help you identify the issue with your noisy A/C and teach you how to fix it easily.


Troubleshooting your loud air conditioner

The good news is that many A/C noise issues are fairly easy to handle, provided you identify them correctly. A key thing to remember is that different sounds may point to different problems. Here are some of the most common noise complaints homeowners have about their A/Cs.

Loud noise from ductwork or vents

It’s reasonable to hear air rushing through the A/C vents in normal conditions. That sound shouldn’t be louder than the swish of a gust of wind. Anything more than a gentle noise coming from the ductwork or vents could signal an issue. The most common explanation for such noises is airflow obstruction, which means something in the ductwork or vents interrupts the free flow of air. 

Airflow obstruction is usually caused by accumulated dust, debris or litter clogging up the ductwork. In rare cases, a small bird or animal could be stuck in the system. In such cases, an HVAC system technician can inspect and clean it to set things right. A second reason for the problem could be the size and shape of your ductwork. 

Undersize ducts or ductwork with too many bends or sharp angles could also interfere with airflow. These design conditions can increase air velocity inside the ducts. Air straining to pass through insufficient passageways creates noises in the process. If you think that could be the problem, have a technician inspect your ductwork. They can tell you if it needs to be redesigned or if it’s simply a matter of fixing a sharp angle or a bend.

A loud whistling noise

Unlike sounds from the ductwork and vents, a high-pitched whistling or screeching noise from your A/C unit can indicate a more serious issue. It usually begins when the A/C turns on and lasts 10 to 20 seconds. This could be accompanied by your A/C unit stopping and starting more frequently than usual. 

If this is the problem, you need to switch off the A/C immediately and call for a technician. The compressor is the heart of an A/C and controls all other unit components. More accurately, it is the part of an A/C that circulates refrigerant to remove hot air and humidity from inside your home to regulate interior temperature. 

Several things can cause an abnormal pressure buildup inside the compressor, and it will take a trained professional to diagnose the exact cause. Your best bet is to turn off the A/C immediately at the sound of a whistling noise and keep it turned off until a technician identifies and fixes the problem. Failing to do so can have catastrophic consequences for the entire air-conditioning unit.

Hissing noise coming from your air conditioner

An occasional hissing sound in your A/C unit that lasts for a few seconds is nothing to worry about, but a persistent one could signal a problem. A hissing sound in your A/C could signal a refrigerant leak. Refrigerant gas is a vital component of your air conditioner. It works as a heat exchanger, cooling down the air inside your home by absorbing heat and dispersing it outside. It is a closed-loop system between your A/C’s outdoor and indoor units. A leak in this important system can seriously hamper your A/C’s ability to cool your home. 

Leaks can occur in the internal refrigerant lines or one of the system valves. In either case, an unchecked leak will likely worsen the problem and cause the hissing sound to intensify. The refrigerant gas in your A/C — known as Freon — can be harmful to human health. So, it’s best to turn off your A/C if the noise is particularly loud or if other noises start to accompany it. Call an HVAC technician to check the problem and fix it before turning your A/C back on.

You ideally want your home appliances to work in the background and not make a buzz. A buzzing noise anywhere in the A/C system can indicate an electrical problem. Trying to repair electrical issues with a DIY approach can be dangerous. 

A buzzing noise in your A/C could mean one of several possible problems:

  • Loose wiring. A loose or damaged wire that comes undone from the A/C’s circuit breaker can sometimes result in a buzzing noise. 
  • Bad circuit breaker. A malfunctioning circuit breaker will not trip, even when too much electricity flows through the wiring. This could produce a buzzing sound as well. 
  • Capacitor fault. A capacitor is a small, cylindrical device in your outdoor A/C unit that stores, supplies and regulates electricity. A bad capacitor can also cause a buzzing noise in your A/C. 

These conditions require a technician to open your A/C’s outdoor unit to identify and fix them. It’s best to keep your A/C turned off until that happens to prevent any further problems. 

Banging sounds from the outdoor unit

A banging sound from the A/C’s outdoor unit usually points to a problem with the compressor. In old A/C units, a connecting rod or crankshaft loosened from wear and tear could cause this noise. These parts can strike against the metal shell of the compressor, resulting in banging sounds. You may need to replace the compressor because some repairs are impossible without damaging the outer casing.  

Other factors can cause a banging noise, including:

  • Fan blade. A misaligned or loose fan blade can also cause a banging noise as it strikes against other parts of the A/C. 
  • Debris. Rocks, leaves or sticks inside the A/C’s outdoor unit can cause similar banging or rattling noises. 
  • Loose panel. An improperly secured outer panel following maintenance or installation can cause loud bangs as the A/C kicks in. 
  • Loose partsBanging noises can also come from any part of the A/C  shaken loose due to normal wear that grinds against other components. 

These problems require minor fixes once a technician inspects your outdoor unit. It’s advisable to keep your A/C turned off until then to prevent any further complications.


4 ways to make your A/C unit run quieter

A properly functioning air conditioner is ideally felt, not heard. It’s natural for a complex piece of machinery like an A/C to make some noise — but not the kind that makes you sit up and take notice. Here are a few measures to ensure your A/C doesn’t develop a large problem. 

Install your A/C unit in the right location

There are several ways to ensure you place your A/C unit optimally for the least noise when building or remodeling. 

  • Place the outdoor unit on the north side of your home. This will ensure your A/C catches the least amount of direct sunlight. A shaded unit works less to cool your home, reducing noise levels. 
  • Keep your A/C away from trees. Vegetation of all kinds is likely to cause leaves, brush and other debris to affect your A/C and compromise its functioning. Debris inside the outdoor unit or in the ductwork is likely to make it noisier. 
  • Keep the indoor unit as close to the center of your home as possible. This will reduce the amount of ductwork necessary and eliminate sounds caused by sharp angles and bends.
  • Avoid installing outdoor units near surfaces like walls and eaves that conduct sound. Position them near surfaces like wood and foam, which absorb sound.

Add sound barriers to your home

It’s natural for the outdoor unit of an A/C to be noisy. You can install one of several noise-reduction measures to ensure the noise doesn’t carry inside your home (or your neighbor’s home). Noise-absorbing fences, barriers, compartments and acoustic blankets all help limit A/C noises. They will not cut the noise entirely, but they will bring it down to an acceptable level. Work with an architect with experience in acoustic barrier installation to decide which solution works best for you. 

A natural way to supplement these efforts is to have enough plants and trees around the house (though not near the A/C unit). Organic materials like rough bark and thick leaves are natural sound absorbers. Enough vegetation around and inside the house will dampen the sound of your A/C. 

Maintain your air conditioner regularly

Machinery works best when it is well-oiled and regularly maintained. That goes for your car, dishwasher and A/C. Fan blades, filters, condenser coils and many other parts of your A/C require regular maintenance for optimal performance. Think of any unnatural noises in your A/C as a call for help. Fix it early, and you’re good. Neglect it, and chances are a minor problem will eventually become a major one. 

Regular inspections and tune ups can ensure many of the conditions that cause noise issues never develop. Periodically replacing filters and refrigerant gas helps your A/C stay in top working order. 

If all else fails, invest in a new air conditioner

The typical air conditioner has an average life span of 10 to 15 years. The life span depends on several factors, like build quality, operating conditions, and timely inspection and maintenance. 

You can assume it’s time to let your old A/C go if you face either of these two problems:

  • Frequent breakdowns. HVAC repair technicians can ensure the smooth functioning of your A/C throughout its lifetime with regular inspections. However, if you still experience breakdowns despite regular maintenance, it can be a sign your A/C is on its way to becoming inoperable.
  • Higher energy bills. Surging power bills without any corresponding change in A/C usage habits could indicate your A/C is no longer as efficient as possible. Once the cost-benefit advantage of repairing that A/C is lost, it’s best to consider replacing it. The cost of buying a new A/C will likely be compensated over time by reduced power bills.


How much does it cost to repair or replace an air conditioner?

Common A/C repairs cost between $168 and $610 (the average is $387). These repairs can include fixes to valves and blowers or a system recharge. 

Air-conditioner repair costs also depend on the size of the unit, as replacement parts for larger A/Cs cost more. The actual fee depends on the issue, labor costs and the A/C’s warranty status. Most manufacturer warranties cover the cost of replacement parts but not labor charges. The average replacement cost of an A/C system can range from $5,000 to $10,000. New ductwork will put you out another $6,000 to $12,000. 

A home warranty plan can save you thousands of dollars in A/C repair and replacement costs.


Protect your home from costly A/C unit repairs with a Cinch warranty

Your home stays cool and comfortable through the summers thanks to a complex and expensive A/C system. But without a home warranty, you’re liable to pay out of pocket every time it needs a repair or replacement. 

A Cinch Built-in Systems plan covers your entire air-conditioning system and all the nagging problems that come with it. Our plan covers the cost of most repairs and replacements. Cinch offers a 180-day workmanship guarantee with a team of highly experienced professionals. 

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Is your air conditioner making too much noise for comfort? Find out why and learn how to fix it.