6 Loud Air Conditioning Noises and Their Causes

Is there a loud noise coming from your air conditioner, and you’re not sure why?

Most AC systems make a humming noise while running— that’s normal. But if the noise is abnormally loud, that could indicate a bigger problem.

To help you troubleshoot, we’ll take a look at 6 common noises your AC could be making and their causes below. First, let’s categorize what the sound coming from your AC is.

If your AC is making any of the following loud noises, make sure to keep reading to find the solution:

1. Hissing
2. Rattling
3. Screeching
4. Buzzing
5. Squeaking
6. Whistling

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If your AC is making a hissing noise, it’s possible that your refrigerant line may have a leak.

Refrigerant is a cooling chemical agent and is a critical component of how your AC system cools your inside air. When warm indoor air enters your AC system, the refrigerant absorbs the excess heat and then releases the heat outside.

if there’s damage to the refrigerant line, a hissing noise can occur as the gases within the refrigerant make contact with the external air.

As a highly toxic substance, refrigerant leak concerns should only be handled by trained professionals. If your AC is making a hissing noise and you suspect this is the cause, call an HVAC expert right away.

If your air conditioner is making a rattling noise, it could be caused by debris or damaged/loose parts.

Sometimes yard debris like leaves, sticks or rocks can get trapped inside your outdoor AC unit (i.e. that big box outside your home). If your AC is running, the debris will make a loud noise as it rattles around.

The same is true for a potentially damaged part that’s fallen loose. In this case, the part freely bouncing around inside your outdoor unit could cause further damage.

If you happen to hear a loud rattling noise, call an HVAC professional for an AC tune-up. During the service, the professional will clean your unit of debris as well as inspect it for damaged or loose parts

If you hear a screeching noise coming from outside, there’s probably an issue with your AC’s compressor.

Your compressor is what pumps the liquid refrigerant throughout your AC system. It is a critical part of your system and is considered the “heart” of it. Most compressors last around 10 years, so if your air conditioner is older than that, it may just be time for a replacement.

If the screeching noise is coming from inside your home, you probably have an issue with your AC’s blower motor.

The blower motor is what pushes cool air throughout your home. This part tends to wear out faster due to heavy usage.

If you hear a screeching noise and suspect you might have a broken compressor or blower motor, contact a qualified AC technician to inspect the parts. They’ll be able to diagnose the issue and assess whether you need a repair or replacement.

If you hear a loud buzzing noise, it’s probably an electrical issue.

You may have a damaged circuit breaker (either due to age or non-code compliant wiring), or you could have a broken capacitor.

Beyond the buzzing noise, you can tell if your circuit breaker is potentially broken if it’s hot to the touch or if you smell a burning odor while near it.

Similarly, if your AC is having issues starting up combined with the buzzing noise, that’s when you can tell your capacitor is having issues. This is because the capacitor is your AC’s electrical powerhouse and stores the power needed to kickstart your system. If it’s damaged, it won’t be able to provide enough juice for the system to start up.

If you suspect that your circuit breaker or capacitor is broken, reach out to a licensed technician for a full inspection.

A squeaking noise often indicates a loose fan belt inside your indoor AC unit. The fan belt may be falling off its tracks, which produces a squeaking noise every time it slips off.

However, this typically only affects older models, as newer ACs tend to be built with direct drive motors.

If your AC is on the older side and you’re hearing a squeaking sound, call an AC technician for an inspection.

Whistling noises often indicate an issue with your air ducts.

If your ducts are too small to accommodate the amount of air being pushed through or if there’s a leak or damage to them, you’ll hear a whistling noise. The noise is caused by air creating friction as it attempts to move throughout your air duct system.

If you’re hearing a whistling noise, call an HVAC technician for an air duct inspection. They’ll help you determine if your ducts need a patchwork repair or complete replacement

Our team of highly trained, skilled AC technicians will conduct a thorough inspection of your air conditioning unit. Whether you have a central AC or a ductless unit, we’ll get your equipment performing as efficiently as possible.

At Advanced Air, we deliver upfront, transparent prices and 100% satisfaction for every job completed. Give us a call at (888) 853-5143 and see why we’ve earned hundreds of 5-star ratings!