10 Types of Air Conditioner Noises: Is This normal?

Huynh NguyenJuly 20, 2022

One can hardly survive an Arizona summer without air conditioning. However, a noisy unit can quickly take away that unmatched joy that can be found in napping on the sofa in the cool air after having been out in the hot sun for any length of time. While some noises are typical of most HVAC systems, if you hear a loud noise that wasn’t there before, it’s a sure sign of trouble.

Let’s look at some of the most common sources of air conditioner noises that aren’t normal and discuss their most common causes. If you hear any of these noises and can’t correct the situation alone, it is a good idea to get in touch with your local HVAC company to learn more about what needs to be done to get back your quiet time.

Banging noises can happen for a variety of reasons. The indoor blower may be out of balance. It could also be a damaged component or even the crankshaft that has caused the noise as it clanks against the compressor. There is rarely a cause for this that won’t require a service technician so if you are hearing banging noises, it’s best to pick up the phone and request repairs.
Clicking noises that happen during the operation of your unit rather than just on startup or shutdown can indicate that the unit’s electrical parts are experiencing an issue. You might need a new thermostat or you might have a faulty control panel that will need to be replaced. A knowledgeable technician can quickly determine the cause and make repairs.
Clanking noises are usually caused by metal on metal contact. An unbalanced blower or loose compressor can cause this. An HVAC technician can correct the problem or replace a bad component to put an end to the noise it is making. Ignoring the problem can result in a much larger repair being needed or complete failure of the system, requiring a full replacement.
Rattling noises can be as simple as pebbles, twigs, or other objects that have blown into an outside component, such as your fan. Turn your unit off, check the outside portion of the unit for any obstructions, and remove them. You might have a screw, bolt, or fan part that has worked its way loose if none are found. You can correct this yourself if you can find it and get to it; otherwise, you’ll need to call a professional.
Loud buzzing noises are indicative that something is not right with your system. The usual culprit is some electrical issue that needs to be corrected. Your contactors or relays may be the cause of the issue. You should never let anything that involves your home’s electrical health go unattended. You are best off powering down the HVAC system and contacting a professional for help.
Humming noises usually originate from the fan. It may just need to be cleaned, but it could also mean the fan blades have gotten warped or bent, the fan motor is in decline or some other component has worn out. If you can turn off the unit and clean the blades, then you may have the problem corrected in short order. For anything beyond that, contact a professional.
Hissing noises when you turn on your air conditioner are not something you should ignore. They can be a sign that pressure has built up to an excess, making the unit very dangerous to leave in operation. Do not leave the unit running. It is best to turn it off immediately and contact a qualified HVAC technician to address the problem right away.
Gurgling noises can sometimes be heard when condensate is draining from the system. It could also be created by refrigerant leaking from your unit. The first may be a bit annoying, but it isn’t usually a huge problem. However, if you are leaking refrigerant, this is bad for your system, your health, and the environment. Shut down your system and do not turn it back on until you’ve had a chance to have it assessed by a professional HVAC repairman.
Whistling noises are a sign that you need to replace or clean a dirty air filter. The whistling sound is possibly caused by air trying to get through a congested filter. A bigger issue that can cause whistling is duct problems. If the size of your ducts is incompatible with your system, you can experience this problem. You might also hear whistles if leaks or cracks have appeared in the duct systems.
Squealing noises are usually the result of a deteriorated belt or bearing in the fan motor. This will cause that annoying, high-pitched squeal you hear indoors. It can also be an indication of malfunction in your compressor or fan’s motor. Seek professional help.