Why is My Air Conditioner So Loud? | Rinaldi's Air Conditioning & Heating

Why is My Air Conditioner So Loud?

How to Identify and Fix Common A/C Noises
Read Time: 4 minutes
Aug 21, 2020
Two workers on the roof of a building working on the air conditioning unit.

AC units today operate at under 55 decibels, making them quiet and unbothersome as they cool your home. If your unit is making squealing, humming, rattling, screaming, clanking, or clicking noises, it’s time to look into the problem. Units will make loud noises while running for a multitude of reasons, from an old air filter to a loose part.

If your unit continues to make loud noises or you can’t identify the problem, seek out professional help to get your unit working correctly. Running a unit despite continuous loud noises can lead to permanent damage to your system.

Keep in mind, if your AC only makes loud noises when starting, the issue could be slightly different. In this article, we break down noises your AC unit may make when running.

AC Noises to Watch Out For

Determining the type of sound your AC unit and attend to issues quickly to conserving your unit’s longevity.


Squealing units emit a continuous high-pitched noise. This usually occurs in the Spring after your AC has been exposed to the colder winter months. Unfortunately, some units always make this noise. Pay attention to your unit to determine if this is a new problem or simply the way your unit operates. While you’ll have to deal with the noise if it’s normal for your unit, you can also avoid a major repair.

Cause: Bad motor and fan or malfunctioning blower wheel
Fix: Replace the malfunctioning part
Urgency: Moderate


Man repairing HVAC system

Humming is a result of vibration within the unit. This can be caused by loose parts, refrigerant lines, and electrical problems. While you can sometimes attend to loose parts on your own, electrical problems are best left to the experts. This isn’t a problem you want to ignore as certain causes can lead to additional repairs.

Cause: Loose parts, refrigerant lines, electrical problems
Fix: Call your HVAC professional
Urgency: Moderate to High


A rattling noise will begin when your A/C unit begins to age and its parts loosen. Other problems include debris that has fallen into the unit and problems with an electrical contractor. If the problem is the electrical contractor it’s best to fix the problem as quickly as possible as this can cause extensive damage to other parts of the unit.

Cause: Loose parts
Fix: Check for loose screw and bolts
Urgency: Moderate to High


A screaming unit is an urgent issue. If your unit sounds like metal is grinding against metal shut it off immediately and contact a local HVAC professional. Screaming could be a sign of a refrigerant leak or high internal pressure within the system. Both situations could result in danger for your family.

Cause: Refrigerant leak or high internal pressure
Fix: Shut off your unit and call an HVAC professional immediately.
Urgency: High

Contact Us for A/C Repair


Clanking is likely caused by one of two things. One potential cause is that the compressor is failing and needs a potential replacement or maintenance. Clanking can also be caused by the fan becoming off-balance and hitting other parts within the system. Both issues need to be addressed quickly to avoid further costly repairs caused by existing problems.

Cause: Failing compressor or off-balance parts
Fix: Replace compressor or fix off-balance blower and fan
Urgency: Moderate to High


Constant clicking, not just when turning on or off, is a sign of an underlying problem within your system. This is likely an electrical problem and can indicate a failing thermostat. Tend to electrical problems quickly to avoid further damage to your unit.

Cause: Electrical problems or failing thermostat
Fix: Contact an HVAC technician to repair any electrical issues
Urgency: Moderate to High

How to Prevent Loud AC Noises in the Future

You can’t prevent every problem that arises in your system as some issues are unavoidable with an aging unit. Most units have a lifespan of 15 to 20 years before parts begin breaking and the entire unit may need to be replaced. However, proper A/C maintenance will help to significantly reduce these problems.

Consistently Change Air Filter

Woman cleaning ac filter

Changing your air filter as needed is a good habit for A/C maintenance. Many problems can begin when something as simple as a dirty air filter is ignored for months on end. Change your air filter every 90 days to prevent any easily-preventable problems from starting.

Schedule Regular Maintenance Inspections

Making time for regular maintenance by an HVAC professional will reduce repairs in the long-term. Have a technician check your unit once or twice each year to catch any rising problems in the system. Your technician will also perform maintenance that will help your system operate more efficiently.

Regular maintenance inspections can cut down repair costs and the inconvenience of a broken unit.

Don’t Wait to Fix Existing Problems

Ignoring a loud, persistent noise coming from your A/C unit can cause permanent damage and increase repair costs. It’s better to have your system assessed by an HVAC professional as soon as you recognize there’s a problem.

Unattended A/C units can cause enough damage to itself that the unit may need to be entirely replaced. A small repair fee is much better than the cost for the complete replacement of major parts or the unit altogether.

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