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7 HVAC Noises That Should Worry You

HVAC Noises

When your HVAC system hums along nicely in your Moody, Alabama, home, you may not even notice that it’s running. Modern air conditioners and furnaces run quietly, and you can barely hear them. However, if you suddenly hear unusual sounds or noises, then something is wrong and the system needs addressing. If you hear any of these seven noises coming from your HVAC system, you need to have it inspected.


Rattling sounds generally indicate something is loose and is blowing around. Even something as small as a screw that comes loose can cause significant damage if left unchecked. If you hear rattling, turn off the system. If you can see something that came loose, remove it and then have it fixed or replaced.


Whistling sounds are never a good sign. It is quite probable that the refrigerant lines are leaking, and because this is a chemical that needs handling by specially trained technicians, you need to have it repaired right away. The refrigerant flows through lines at high pressure, and if a leak occurs, it can pour out rapidly. Not only is the coolant dangerous to handle, but lack of it in the air conditioning system can result in expensive damage to the system. Don’t try and DIY on anything relating to the refrigerant.

Hissing or Bubbling

Generally, hissing noises are a result of air leaking from somewhere. If you hear it inside of your walls or attic, most likely there is a crack in the ducting system allowing air to leak out. While this is not a panic situation, your treated air is leaking out into the walls or attic instead of into your home where you want it to heat or cool your house. Have your duct work checked and make necessary repairs so you don’t waste energy.

Clanking or Banging

Clanking and banging noises are usually a result of metal scraping against metal, which is not normal for your HVAC system. Loose fan blades or broken parts flying around inside of the HVAC housing compartment causes further damage to the rest of the system. Parts that have broken off not only cause damage to other parts of the system, but it puts extra strain on it. Having the air conditioner or heater running with missing or broken parts reduces its efficiency as well as its life span.

Frequent Clicking

While some clicking is normal, especially when the system first starts, excessive clicking could indicate an electrical issue. You don’t want to mess with any electrical issues as they could result in a fire. You will hear frequent clicking if the start capacitor, the motor’s control board or fan motor is having trouble. Turn the system off and have it inspected.


While a sudden popping noise can give you a start and surprise you, popping noises are fairly common with an HVAC system. As the metal duct work expands and contracts due to temperature variances, it makes popping sounds. However, if the popping becomes louder than normal, the ducting might need a good cleaning, repairs, or sealing. Ducting made with thicker-gauge sheet metal can withstand pressure differences better than those made with thinner metal and make fewer popping noises. Consider upgrading your duct work if the problem persists or annoys you.


Buzzing sounds result from excess vibration. Connections within the air conditioner, furnace, or heat pump may have loosened and needs either replacement or re-connection. If the buzzing is strong and insistent, it means the motor is not running well and may break down. Anytime there is a problem with electrical components, the motor, the compressor, or the coils, your HVAC system has to work harder and harder to deliver warm or cool air to your home. An overworked system needs more repairs and reduces the life expectancy of the system.

Your HVAC investment is one of the largest you will make for your home. Have regular maintenance to make sure it performs efficiently throughout its intended life span. Give our knowledgeable team at Total Comfort Heating and Air a call today to sign up for our maintenance plan so your HVAC system runs smoothly and efficiently all year-round. We look forward to speaking with you at (205) 386-2056.

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