Why My AC Unit Makes Loud Noise When Starting?

There are days that the heat and humidity are just too much, making us want to have an Air Conditioner in our homes. You’re lucky enough if you already own one. But it’s quite a concern if you hear loud noises from your air conditioner especially when it’s starting. You certainly need to call a professional HVAC technician to avoid making your AC dysfunctional. While waiting you can check out the following possible causes of the noise your AC is making. 

Banging and Clanging

There are two possible causes for this noise. It can either be the cause of debris stuck on your unit, or a loose fan that hits against the HVAC cage. Upon hearing this noise, you should immediately shut it down to avoid further damages and complications. You should call professional HVAC technicians for this is an urgent concern. 

The Rattling of the Outdoor Unit

It is truly inevitable for anything to age. Like other equipment, air conditioners also deteriorate as time passes by. As it ages, the parts loosen and that’s what makes the rattling sound. However, if it’s not that old yet, several possible reasons include a loose fan, malfunctioning electrical contractor, or it has twigs and leaves stuck inside. To avoid further damage, it’s commendable to immediately call a professional HVAC technician. 

High-Pitched Screaming or Whistling

This noise surely needs immediate action from professionals. This is one of the most serious signals that an AC can send to its owner. There are two possible reasons for this. Either there’s a refrigerant leak or there’s an issue with the compressor. Either of the two, you have to take quick action on this noise. Some AC offers a safety feature that shuts down the unit in case this instance happens. But if not, shut it by yourself and don’t operate until it gets inspected by a professional. 


Whenever you start it, if it produces clicking sounds and doesn’t turn on, it can be a cause of the electrical problem. In case this occurs, it’s best to leave the work to professionals. 


Squealing can also be caused by two possible reasons. Either it’s caused by a misaligned or worn fan belt, or a malfunctioning outdoor fan motor or indoor blower motor. The sound may come and go when the belt is the cause because it’s the temperature that makes the fan belt contract and expands. However, you should still consult it with a professional. 


Humming is not much of a problem. However, leaving it unchecked for a long time may cause bigger problems. It can be caused by loose parts or refrigerant piping. It could also be an issue with the motor if it hums and the compressor doesn’t start. Whatever the reason is, the best way to resolve is to call an HVAC technician. 

Metal Popping

This is the least to be concerned about. It’s usually the ductwork while it responds to the unit to turn it on or off. However, you can buy some type of insulation or foam to reduce the noise. 

To avoid those noises made by ACs, you might as well want to do the following preventive measures: 

Schedule Regular Inspection

To keep your HVAC in good condition, you better schedule a maintenance inspection for at least twice a year. This will help you know what possible problems your AC may experience and avoid it before it happens. 

Install Noise-Reducing Barrier

In case you just happen to have a noisy air conditioner, try to buy a noise-reducing barrier. It can be a noise-reducing fence, sound blanket, or quiet fence. 

Immediately Call an Expert

If you are suspecting that your AC has problems, don’t hesitate to call an HVAC technician to inspect. That way, you won’t have to face big damages and pay more money and time. 

These are all the following reasons why your AC creates noises whenever it starts. In case any of these fit with your concern, immediately call a professional HVAC technician. Also, remember to follow all preventive measures to avoid complications and worse, a fully damaged AC.