When someone asks us, “why does my air conditioner sound like a jet engine?” I often respond with, “why is your truck so loud?”
Just as with your truck, an air conditioner is a modern complex piece of machinery, so it’s normal that your air conditioner makes noises.
So, figuring out why your air conditioner is so loud is far too complex a question to address in one article.
Instead, we will focus on a few of the most common causes of a noisy AC.
Common Reasons Why Your Air Conditioner Sounds Like a Jet Engine
If your heat pump or AC sounds like a jet engine, clearly, you have a problem. The most common reasons include a squealing fan motor, rattling exterior unit, rattling AC ducts, and faulty components such as failing condensing fans, blower fans, and compressors.
Just as with your car, if it starts to make a harsh, grinding sound, it’s probably best to leave it to a licensed HVAC technician.
But that doesn’t mean you should rush to your phone the second you hear your air conditioning system squealing.
In general, a change in how your air conditioning sounds is a bad sign, but that doesn’t mean that it isn’t an easy fix.
Here are a few things to check out when you hear strange air conditioner noises, most of which you can do yourself with just a little time and some basic household tools.
Though we reference air conditioners in this article, the same can be applied to heat pump noises.
⭐ Why is My AC So Loud? First, Ask Where…
The first part of figuring out why you have a noisy air conditioner is to get an idea of where the sound comes from and what type of sound it is.
Is it coming from the compressor, or is it the fan itself? What about the condenser coil, which also has a fan over it?
To understand this, you need a basic understanding of how air conditioning works and what parts it has, so if any of this is new to you, then start here – don’t worry, it sounds worse than it is.
Before doing any maintenance on your noisy air conditioner, start by turning your HVAC circuit breaker to the OFF position in your main CB panel, remove the disconnect (if applicable), and turn your air conditioner off with your thermostat.
✈️ AC vs Jet Engine Step 1 – Is the Fan Motor Making a Squealing Noise?
Is the jet engine sound coming from the fan motor?
A central AC unit is similar to a Split AC or Ductless AC because they all have an interior and exterior unit.
Both of which operate under the same principle. The indoor evaporator and outdoor condenser coils have a fan controlled by a motor to move heat and air.
To examine the exterior air conditioning unit, remove the outer casing to reveal the inner part of the condensing unit – you will notice the fan located right in the middle above the compressor.
If this is your problem, remove debris from the unit and check the fan blades for dents or dings.
A common problem when dealing with a squeaky fan is the debris and dirt accumulating and sticking to the fan blades.
This will cause an imbalanced and noisy fan. This is easily fixed by cleaning the outdoor unit.
The interior fan unit is a little more tricky. Locate your indoor air handler if you have central air conditioning and check for loud noises.
The fan is in each indoor unit if it’s a ductless unit. This fan is less likely to get dirty if you regularly change your filters.
Again, this is best left to an HVAC professional if you have a noisy indoor blower fan.
For information on how to prevent this, see Air Filter Guide: MERV Filter Ratings and What They Mean For Homeowners.
Even the slightest bend or imbalance in an AC fan can cause your blade to scrape its casing, also known as a fan cage. This will make for a very noisy air conditioner. If your blade is damaged, it will need to be replaced.
Also, spin the fan with your hand to ensure it moves smoothly. If loose, make sure to tighten the center bolt. If it’s squeaky, and you’ve tried everything else so far, it’s like the bearings need some lubrication.
The 444 HVAC lubricant is the best for the job and is available at your local hardware store but is unnecessary.
A lubricant such as WD-40 will work just fine in this application. However, if. If the bearings are still noisy or if the blades do not rotate smoothly, call your local HVAC professional, and they can replace your bearings for you.
If you hear a grinding sound, call your HVAC technician as this is a sign of pending bearing failure.
For more information on your AC fan, check out: AC Fan Not Working? The Homeowners Guide to Cool Air
✈️ Step 2 – Rattling from the Exterior Condensing Unit
The next most common cause of rattling is something loose.
For example, if you have isolated the noisy air conditioner to your condensing unit – the outdoor one – (or packaged unit) itself:
- Again start by turning the AC unit OFF, start with the thermostat then the service disconnect, and the circuit breaker.
- Then, check all internal and exterior panels.
- If you find anything loose, tighten them up but check the inside panels first before the outside panels.
When troubleshooting, follow the rule of thumb of working from the inside out when tightening your AC unit’s panels.
✈️ Step 3 – Examining Rattling AC Ducts
Sadly, this requires you to go into the attic. We hope it’s not a hot day!
If you are not experienced with this, ensure to only walk on support joists (the wooden pieces between insulation).
Again, unless you have experience working in attics, we recommend calling your local HVAC contractor.
Check your air ducts for leaks and loose joints and tighten them with duct screws and HVAC tape as necessary.
How? Just use common sense and seal leaks. Try not to overthink it.
If the rattling sounds continue to be a problem, you probably need to call your local HVAC contractor as the installed ducting may not be the correct size.
Related Reading: Leaking Air Ducts Will Cost You Money! Here’s How To Fix It!
✈️ Step 4 – Ask What Kind of AC Sounds Are You Hearing?
Again, before answering the question “Why does my Air Conditioner Sounds Like a Jet Engine,” always start by figuring out the source of the unusual sounds.
It’s very difficult to diagnose an issue if you don’t know where the ac noise is coming from, to begin with!
Once you have localized the problem, another way of diagnosing it is to just stop and listen to the jet sound.
Again, this is easier for us experienced HVAC technicians. For everyone else: here are a few general guidelines.
🔊 Listen with your ears
Seems simple enough, but the more harsh the sound coming from air conditioners is, the more likely it is to be serious. So if it’s so loud it hurts your ears, it’s time to switch off your AC and call in a pro.
🔊 Mild squeaking from your AC
Likely not serious – It’s probably just a bearing that needs lubricant or a dirty fan that is out of balance.
🔊 An AC rattling noise from your ducting, air vents, or the AC itself
Again, not that serious – more than likely it’s just a loose panel that needs tightening or it’s a loose AC duct that requires adjustment.
🔊 That awful grinding noise
Now we are getting serious! This is a bearing that’s about to fail, and if not replaced soon, it will possibly damage other parts of your HVAC unit.
These are common on fast-moving assemblies such as blower fans and condensing unit fans.
🔊 Hissing sounds
Don’t freak out, though, unless you are confident it is coming from the evaporator coil, the condensing coil, or any refrigerant lines and connections.
The hissing noise or whistling sound could also be loose duct work, which isn’t that serious unless it’s Arizona in summer and you need to spend hours in your attic fixing it.
So, when in doubt, give your local HVAC contractor a call, especially if you find a loose or damaged seal that’s beyond your DIY expertise.
If you don’t live in our area (or don’t like us), here are some tips on how to choose a licensed HVAC contractor that will ensure your job is done right: How to Find a Good HVAC Company – Making Smart Choices in 2022
If you want to take care of your air conditioner for years of future use, try: Easy-to-Follow DIY AC Maintenance Guide
Dealing with other common AC problems? Check out: Top 18 Common AC Problems and Solutions
Related reading: The Importance of a Clean Evaporator Coil
⭐ Final Thoughts on Noisy Air Conditioning Units
So, why does the air conditioner sound like a jet engine? Unfortunately, the answer to a noisy air conditioner isn’t that simple.
But in the end, there are always some things that you can do yourself, so don’t be afraid to get your hands dirty.
Sometimes if your attempts at a simple tune-up haven’t worked out, it is just time to call in the pros.