AC Sounds Like a Jet Engine or Helicopter: Causes + Fixes

If you have an older AC unit, it may sound like a jet engine, helicopter, washing machine, or even popcorn when it starts to break down. This is a sign that something in the system is breaking down. So in this post, I’ll go over why an AC makes these loud and concerning noises.

With a quantum leap in HVAC technology, many AC units are designed to operate as quietly as possible without causing unnecessary distraction. Integrating a variable speed compressor and a sound-reducing feature in designing AC units has allowed the noise level emitted to be 55 decibels or less. That is almost the corresponding noise level associated with a dishwasher as it operates.

Although your AC unit should be making some noise, the noise level should not be alarming or loud. If you notice an intrusive jet engine or helicopter sound made by an air conditioner, that indicates equipment that is having issues and needs a repair or replacement straightaway.

Why Does My Air Conditioner Make Odd Sounding Noises?

Suppose your AC sounds like a jet engine or any odd-sounding noise. In that case, it suffers from common mechanical issues associated with the outdoor segment or the indoor AC blower component. Generally, the jet engine sound or a whirring noise of an AC is often caused by issues such as a:

A Faulty Condenser Fan

If the outdoor AC condenser fan’s motor is not working perfectly, it may cause a buzzing or jet engine noise as it operates. A faulty condenser fan may point to its accumulation of debris or an electrical issue.

A Faulty Compressor

An electrical or mechanical issue may also result in your AC releasing a jet engine-like sound due to a defective compressor. A faulty compressor may occur because of an issue such as the delivery of imprecise amperage by the relay switch.

Frozen AC Evaporator Coils

Sometimes the coils inside the AC’s central air system accumulate ice, leading to their freeze-up. The freezing of the evaporator coils may be due to refrigerant leaks, often resulting from a lack of sufficient air circulation, troublesome refrigerant piping, or a spoiled expansion valve.  

Other possible causes of a jet sound produced by an AC include a malfunctioning blower fan motor,  a deficient fan belt in the system, or unfastened components. For instance, in terms of loose components, it is possible to experience insecure fan blades, which may also result in the emission of the helicopter or jet engine-like sound.

Troubleshooting the Noise in an AC

Whenever your air conditioner creates noise, there are a couple of potential sources of the problem. In this case, what is most important is to ensure you are dealing with a jet engine-like noise and not any other unusual sounds such as banging, buzzing, clanking, and squealing. Different noises or sounds emanate from different AC parts.

To troubleshoot an AC with a jet engine sound, you first need to identify the potential sources of the annoying problem. For that reason, you may have to check for mechanical issues such as:

• Loose components such as screws and bolts
• Accumulation of dirt in the outdoor/indoor unit
• Unbalanced or insecure fan blades
• Copper lines of the AC suffering from abrasion
• The dirty coil of the condenser
• Ineffective air filter
• Unbalanced or deteriorating blower
• A refrigerant leakage: This causes the freezing up of your air conditioner not to allow its refrigeration inside, even if the unit seems to be in good working condition from the outside.  

Reasons For Jet Engine-like Noise in an AC

1. Refrigerant Leak

This is one of the common reasons why your AC may be producing jet engine-like noise. Leaking of an AC refrigerant can result from the destruction of the AC refrigerant line. With the continued use of your AC, the lines become more susceptible to damage, leading to leakage.

There is no do-it-yourself solution for fixing this particular AC issue. A leaking refrigerant issue is best solved by an HVAC expert who understands what should be done.  

• Broken or fatigued AC Belt

As one of the potential causes of jet engine noise, the issue is often common in central or ducted air conditioning units. The belt plays a vital role in an AC by connecting the fan and the motor. Over time, the belt suffers from wear and tear, which can cause the creation of a jet engine-like noise. Also, during the summer, the belt can cause this type of noise since it is heavily subjected to contraction and expansion because of the high humidity level.

The best solution is to solicit the service of an HVAC professional for the belt to either be subjected to replacement or repair.

• Damaged Compressor/Fan Motor

If the AC is switched on and you hear the release of a jet-like sound, the issue may be related to a problematic compressor. Regrettably, the replacement of a compressor of the AC or fan motor is quite an expensive affair. Still, if your AC has served you faithfully for more than ten to fifteen years, it is best to replace it instead of engaging in expensive, wasteful repairs.

For any repair, whether the noise is caused by an unusable fan motor/compressor, that should be done by an air conditioner specialist. A specialist is better positioned to advise you accordingly if HVAC repair/replacement is the way to go.

• Loose Components

Whenever you switch on an air conditioner, both the exterior and interior components are subjected to vibration. As time goes on, the vibration may lead to loosening AC screws and bolts.

Fixing this particular source of AC noise is simple as you only need to possess and use a screwdriver to secure any loose screws and bolts.

• Debris Accumulation

Leaves and other dirt particles usually get attracted to and stuck in the AC condenser, mainly if the outside AC unit sits adjacent to shrubs.

This issue of debris accumulation, which may cause your AC unit to release a jet-like sound, is also easy to solve. You only need to remove the AC condenser cover to get rid of the litter and dirt. If you are not able to undertake the cleaning task, you can contact a professional for timely assistance.

• Loose-fitting Fan Blade/Coil

Over time, the fan blade/coil loosens, a potential cause of this particular air conditioner noise. Just performing a simple screw tightening will guarantee that your AC unit reverts to producing its normal noise.

• Refrigerant Lines Contact 

When the copper AC refrigerant lines rub against a thing like a wall, that can also lead to the emission of the jet engine-like sound. The refrigerant lines should not be rubbing against anything. You can add an insulation material, like rubber, to safeguard the lines against direct contact with a wall or anything else. Avoid any possible metal-on-metal exposure.

• Evaporator and Condenser Coil

If your AC evaporator or condenser coil is frozen or dirty, that should be a cause of concern. Try cleaning your coil regularly to free it from dust, frost, or debris. Ensure the frozen coil is thoroughly left to defrost by turning off the AC unit before switching it on again. If the noise issue is not resolved, it may be the right time to dig deep into your pocket to replace the unit.

• Ineffective AC Filter

An ineffective filter such as one with the accumulation of dirt is liable to cause you lots of problems than you may have imagined possible. A filter with issues may even cause the complete shutting down of your AC unit. To ensure your system operates without problems, you should replace your existing filter every month.

1. Sealed Bearings

For an AC unit with motors and fans having sealed bearings, they should be oiled regularly. And ensure you adhere to the manufacturer’s instructions when lubricating the bearings.

In conclusion, it should be evident that when your AC sounds like a jet engine or helicopter or produces any undesired noise regularly, it indicates an issue with your system. If you ignore the unwarranted sounds released by your AC, you will have to deal with a more severe and costly problem. Therefore, always be on alert to recognize an unusual AC noise and hire the service of an HVAC professional to fix the issue without delay.

Tim David

HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.