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Commercial Air Conditioning, Commercial HVAC

Why is my AC making a loud noise?

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Last Updated on January 15, 2020


noisy air conditioner

Is your noisy air conditioner about to break down?

The cool air provided by your air conditioning system gives you welcome relief from the heat, but the noise coming from your air conditioner is quite another story. A noisy air conditioner that’s always been loud might not necessarily have a problem. However, if you’re hearing an unusual air conditioner noise like banging, buzzing, whistling, screeching or rattling, it can be a symptom of a system that’s struggling and headed for a breakdown.

The same is true for one that’s running constantly and running louder than usual.

Common causes of air conditioner noise are related to:

  • damaged ducts or poor duct design
  • clogged filters
  • loose parts
  • bearings and belts
  • electrical issues
  • fan problems
  • coil damage

Let’s take a look at the reasons behind the specific air conditioner noise you may be noticing, and what can be done to quiet your noisy air conditioner down.

Your air conditioner noise and what it means

When your air conditioner is making noise, listening to the specific sound you’re hearing can provide a clue about what’s wrong with the equipment. Keep reading to learn the common causes of noises you might hear coming from your air conditioner.

Having that information can help you decide if you need to call in the pros immediately, or if you might be able to wait until your next maintenance appointment. You might even be able to handle it yourself.

Whining and whistling noise

Is your air conditioner plagued by whistling and whining noises? These annoying sounds could signal airflow problems. Here are some of the ventilation issues causing your noisy air conditioner:

  • Incompatible ducts and HVAC equipment. If your HVAC unit parts have been replaced piecemeal over the years, you can end up with parts that don’t work well together. For example, the ductwork might be too small for the air blowing through the system, which could result in a whistling sound coming from your air conditioner vents.
  • Damaged ducts. It’s not unusual for ductwork to develop cracks and leaks over the years. Air can escape through these openings and produce a whistling sound.
  • Clogged filters. Air filters, which are designed to catch dust and other particles and contaminants, will become full at some point. When the filters reach capacity, airflow can be blocked, which will cause air conditioner noise. Changing or cleaning the filter is a job you can do yourself.

Shaking and rattling noise

Rattling sounds typically come from loose air conditioner parts. Parts of the system that are subjected to a lot of movement, such as motors, can come loose. Ducts can also come loose.

Your noisy air conditioner could be the result of one or more of the screws in your AC panels shaking loose. In that case, a screwdriver is all it might take to silence the rattling.

Your air conditioner unit itself might not be properly secured to its concrete footing if a mounting screw has come loose. Though weekend warriors may be tempted to try and stabilize your noisy air conditioner by yourself, it’s smarter to call in a trained HVAC professional to avoid the dangers of contact with hazardous chemicals and high voltage electricity.

Squeaking, squealing, or screeching noise

If you’re hearing high-pitched noises coming from your air conditioner, have an HVAC professional look at your system’s compressor and fan motors. These types of air conditioner noise often are the result of unlubricated bearings or slipped or damaged blower belts.

Loud buzzing noise

Most of the time, a buzzing sound comes from an electrical problem. If you are hearing a clicking sound, it could mean your systems relays or contractors are failing. Definitely call in a professional to fix this type of air conditioner noise problem.

Humming noise

In order for an air conditioner’s fan to run properly, it must be regularly maintained and kept clean. A rattling or humming fan likely needs a good cleaning. A worn-out part in the fan, problems within the fan motor, or bent or shifted blades could also cause this air conditioner noise.

Hissing noise

If you are hearing a hissing noise coming from your air conditioning unit, it could be caused by a refrigerant leak. If that’s the case, you may also notice that your system is running more often and not cooling as well. It’s time to call in an HVAC professional and have your refrigerant charge, coils and lines checked for possible leaks.

TIP: Refrigerant leaks are often caused by neglected maintenance. Coils that are not regularly cleaned get corroded, resulting in small holes and cracks where refrigerant leaks out. You can prevent this problem by getting a preventative maintenance plan with a reputable HVAC company.

Constant running noise

A problem with your AC coils may be responsible for your noisy air conditioner. Bent coil fins can produce a humming sound. If the coil fins become clogged with dirt and grime, your system works less efficiently, and ends up running constantly as it struggles to reach set temperature. If not attended to, this problem will cause a breakdown.

Just because you’re hearing the noise inside the building, be sure to examining your outside condenser unit. It is not unusual for twigs and other debris to get stuck in the condenser unit’s fan. Make sure the area is swept clean of dirt and debris.

Poor system design

Have you been plagued by too much air conditioner noise since your system was installed, with the unit constantly turning on and off? If so, the system may be too large for your space. Or, it may not be outfitted with high quality noise reduction technology.

Stop the noise with routine preventative maintenance

Ready for some peace and quiet along with better comfort conditions? It’s time to schedule an inspection and maintenance visit from an expert HVAC company. Your air conditioner noise is more than just an annoyance. It could be costing you money in terms of operational inefficiency. And it could lead to an inconvenient and expensive system breakdown in the hottest part of the summer.

Plus, you can prevent many air conditioner problems in the future (including noise issues) with regular preventative maintenance.

Should you repair or replace your noisy air conditioner?

In the worst case, you might face with a costly repair estimate to fix your noise problem. Now you have another problem: how to decide if your air conditioner is worth fixing or if you’re better off replacing it?

There are many factors to consider before making a repair or replace decision, including the age and condition of the system, its repair history, and the extent of the current damage. Also, if it uses R22 refrigerant (Freon), which has been phased out, that should also impact your decision.

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