Why is My AC Making Loud Noises

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Why is My AC Making Loud Noises?


10 Warning Sounds from an Air Conditioning Unit and What They Might Mean

Even the best air conditioning units make noises. Some noises are completely normal. For instance, you might hear gentle blowing sounds or revving noises as your AC unit starts up. These sounds are caused by fans or other moving parts gearing up when your AC begins a cycle. You might also hear clicking noises when the unit is shutting down after a cycle. These noises can last for seconds and are no cause for concern. But is your AC making loud noises you haven’t heard before? Should you be concerned?

It all depends on what types of noises you’re hearing. Does it sound like your AC is screaming in agony when you turn it on, or slamming a door every time you shut if off? Air conditioning units are made of several parts that can cause many different noises when things go awry. The key is to find out what is causing any abnormal noises as soon as possible. Ignoring warning signs can turn a minor issue into a major problem, which could possibly involve replacing your entire AC unit.

What Strange or Loud Noises are Coming from Your AC Unit?

Old Air Conditioner

1. My AC is Making a Screaming or Screeching Sound

If you’re hearing sounds from your AC that can be described as screaming, screeching, or whistling, turn your unit off right away. These types of noises may indicate a refrigerant leak that can expose your family to fluorinated hydrocarbons, which can be toxic if inhaled in large amounts. High-pitched noises might also indicate high internal pressure within your compressor. A pressure imbalance can possibly lead to premature failure of the compressor or a system malfunction. This imbalance can cause decreased cooling capacity or a complete system shutdown.

2. My AC is Making a Squeaking or Squealing Sound

For some AC units, squeaking sounds are completely normal as the system starts up. However, new or loud squealing sounds could indicate something is wrong. Squealing noises are actually more common in the springtime after your AC unit has endured the winter elements. Your outdoor fan motors and indoor blower motors could be worn down, which will require you to replace the bearings on your condenser fan or replace your entire fan motor. Squealing noises can also mean that your blower wheel isn’t working properly. If you have an older unit, your belt may have slipped. For these types of problems, you probably want to enlist the help of a professional HVAC technician

3. My AC is Making a Buzzing Sound

Buzzing sounds from your AC can be caused by many different problems. It’s usually caused by loose parts vibrating against something else. Parts of your system, like your outdoor fan motor, may be loose. Other parts, like your fan blades and blower, may be out of balance. Or perhaps you’re hearing the sounds of the copper lines within the system rubbing against something. Buzzing sounds may also indicate that your AC unit is frozen due to a refrigerant leak.

Sometimes buzzing sounds simply mean your AC needs some tender loving care, like minor cleaning and replacements. The condenser coil may need to be cleaned or debris may need to be removed.

4. My AC is Making a Humming Noise

Most AC units naturally make a humming sound as they run. But loud or unusual humming noises can also mean something is not working properly. They might indicate an electrical problem, like a loose wire, or other loose parts, like the fan blade. Loud humming can also indicate a bad motor or that the starting capacitor is beginning to fail.

5. My AC is Making a Knocking or Banging Noise

Loud banging or knocking sounds typically mean something is loose or disconnected in your HVAC unit. When parts come loose, they can easily bang against other parts of the unit. If you hear loud banging sounds, turn your system off right away to prevent further damage. AC parts that are known to come loose are the connecting rod, blower, motor mounts, crankshaft, piston pin, or screws. Banging noises may also indicate a problem with the blower assembly or motor.

6. My AC is Making a Clicking Noise

It’s normal to hear clicking noises when your HVAC units turn on and off. But continual clicking noises coming from the control panel or outside compressor may indicate a defective relay,  possibly caused by an electrical malfunction. The most common cause for clicking noises is a loose fan hitting against something or faulty parts like the relay switch, control board, fan motor, or capacitor. Intermittent clicking noises can also be caused by an AC system struggling due to a malfunctioning thermostat.

7. My AC is Making a Rattling Noise

Rattling sounds usually indicate that there is something loose inside of your AC system. This usually involves the blower assembly, motor mounts, or motor bearings. If you hear a rattling sound from the compressor fan, this may also indicate loose components or a failing motor. You should seek the help of a professional HVAC technician right away to prevent a part from breaking or disconnecting completely.

8. My AC is Making a Slamming Noise

A slamming sound can also be caused by loose parts, like a loose fan slamming against other parts of your AC unit. If this is the case, you may need to tighten the fan or possibly install a whole new fan assembly. A slamming noise may also indicate a problem with your compressor springs. These springs support the refrigerant pump inside of your compressor. If a spring breaks, it can cause the pump to slam against the compressor.

9. My AC is Making a Crackling Noise

A crackling noise coming from your AC could be caused by debris in the unit, like a piece of plastic that was sucked into the unit and wrapped around the fan. Crackling noises can also be caused by older ducts that are vibrating due to deterioration. One of the more serious causes of crackling noises is an electrical fire. Fires in your AC unit can happen if certain wires touch the wire connection point of the AC unit. If you smell something burning by the unit, turn the system off immediately and call the fire department and an HVAC technician.

10. My AC is Making a Popping Noise

If you hear popping sounds coming from your AC while it’s running or right after a cycle stops, this could mean something is blowing through your ducts. If it sounds like something is trapped in your ducts, it’s time to clean your ducts out. Your ducts may also make noise when they contract and expand due to internal temperature changes. A professional HVAC tech will be able to inspect your ducts and minimize the noise by adjusting the actuator or creating a custom solution, like installing acoustic liners or padding.

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Worried about the noises coming from your AC? Don’t stress the whole day. Call John. Get more. Stress less. Call us at (713) 730-2525 or contact us online!

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