Why Is My AC So Loud?

Why Is My AC So Loud?

If you’re reading this, it’s probably because your AC is making some crazy noises lately that you’re not used to.
Or you just moved into a house and the AC has never been used until now, and now, it’s making strange noises.
Of course, it is a machine, and machines make noises.
But why is this thing getting noisier and noisier every summer?
We wanted to share some things we’ve seen out in the field working on other people’s AC systems that might help you isolate where the noise is coming from and some possible reasons why your AC is so loud.
Your air conditioner is very likely on the side of your house. For some people, it’s on the roof and for obvious reasons, a roof-mounted AC is going to make some low consistent vibration because it’s mounted to the roof joists, which are connected to the wall studs, and the rest of the house.

So, for those of you with rooftop air conditioners, that is something you may be stuck with as long as it’s up there.
Also, we’re sure you already know, these are machines and machines make noise.
Typically, the older they get, the louder they get.
So, understanding that, let’s dive into some real issues you might be experiencing on systems that aren’t 20 years or older.
We want to break this into two parts: Things you can fix yourself, and things you might want to have a real HVAC technician look at.
Notice we said real technician and not a person dressed like a technician who is just there to sell you a new system.
These deceiving salesmen and saleswomen are only in it for the money and have no interest in saving your system. Remember, if the parts are available, and yours very likely are, or can at least be retrofitted with correctly matched universal parts, it can be repaired.
You’re in charge.
Your system is designed to last about 20 years before you might start considering getting a newer system.
But, it’s really about where YOU want to put YOUR money and not the technician. Your AC that sits on the side of your house only has a few parts in it that will make some crazy noises.
Inside the shell of that outdoor unit is a compressor, a fan motor, and an on/off switch called a contactor.

The biggest part, the compressor, pumps the refrigerant through your system much like your heart does the blood in your body.
This pumping requires two spiral plates to rotate in an elliptical motion.

And sometimes those plates (more commonly called scrolls) can chip or come out of alignment creating the loudest, most awful noise you’ve ever heard.
Especially, if it happens at night when you’re sleeping.
It’s a grinding noise or a loud clacking noise that can’t be missed.
It’s not like we can take the cover off and look inside to fix it either. It’s a hermetically sealed part that can’t be opened by anyone.

If this noise can’t be fixed from outside the compressor, you will most likely agree with your technician when they say you need to replace that part.
We remember a house that was doing this. The loud noise never stopped for the customer as they ran their AC. It wasn’t even cooling the house either.
It was just running and running and running. As we approached the unit that was completely on the other side of the house, it got louder and louder.
After some testing, we noticed the compressor wasn’t pumping as it should, yet it was still making this loud noise.
This was the loudest air conditioner we have ever heard. It was a 10-year-old Bryant AC, so we changed that compressor out, and the system ran fine from there on out.
We’ve also come upon an AC where the compressor, one just like we were talking about, wasn’t out of alignment or broken, but internally had a part called a by-pass that was stuck open.
This created a loud squealing or screaming noise indicative of high pressures and high heat inside that compressor.
Before replacing this part though, a technician should determine if the refrigerant pressures within the system are adequate, as well as some other tests. Whatever the solution, we just wanted you to be aware of some noises a compressor makes.
Another time we might have to replace the part making the noise and it’s the condenser fan motor.

That’s the fan blade you’ve probably seen that spins on the top of your AC when it’s running.
We’ve come out on a house before where this motor that spins the fan blade is making a high-pitched whistling noise. As we looked around the AC, we isolated the noise coming from this motor.
Every AC fan motor has ball-bearings that help the motor shaft spin. But these bearings are sealed and can’t be accessed to lubricate them, which would likely solve the problem.
So, in this case, the motor has to be replaced if you want the loud noise to cease. Finding the right motor can be tricky too, so it’s probably best to let a qualified technician do it.
Just putting a motor with the wrong speed setting will cause cooling issues you won’t be happy with.
Next, your AC has an on/off switch called a contactor.
The thermostat inside your home tells it when to switch on and off by sending a low voltage signal. Two plates come together at that very moment to allow the high voltage through to the parts – the compressor and the Fan Motor.
As the years go by, pitting caused by the high voltage arcs happening between those two plates, as they come together, can get to a point where the two plates won’t come together all the way. It creates a loud buzzing noise.
Not near as loud as that compressor we were telling you about earlier, but loud enough to get your attention.
Getting into the electrical panel of an air conditioner can be pretty intimidating and dangerous causing electrical shock, so let’s make sure a qualified technician helps you with this.

Once again, getting the wrong switch can lead to more expensive problems.
Now, here are some loud noises you are likely able to isolate and fix yourself, but still, if you don’t feel comfortable doing it, just call Red Deer Heating and Air Conditioning services and our technicians will be happy to fix this stuff for you.

Other Causes of Air Conditioning Noises

First, if your system starts making loud noises, make sure it’s level.

If the AC isn’t flat, oil inside the compressor might not be lubricating the way it should be. Just be careful not to bend the copper lines coming from the wall to the AC. This will strangle the refrigerant and cause more expensive problems.
Next, sometimes sticks and leaves can block the fan blade on top of the AC from spinning, which causes some strange noises with the AC, so definitely go outside and at least check to see if any sticks or toys are preventing the fan blade from spinning.

The damage may already be done to the motor, but you can at least try.
Also, the fan blade is protected by a round metal shroud that is there to allow warm air to flow out of it, but also protect people from getting their fingers inside of the AC.
Sometimes this shroud starts rattling as the screws that hold it down start vibrating loose, possibly creating a larger hole than the screws were initially sized for.

As the AC runs, the rattling can get pretty annoying. This tends to happen in older systems.
The solution would be to install a little bit wider screws that could hold the shroud down more securely. This would fill the hole better and create less noise.
Another trick we like to do is get these little rubber isolation pads and use them as shims to help dampen the vibration between the shroud and the frame of the AC.
This can help in reducing the vibration or rattling noise on your aging system.
Preventive maintenance is the key. If Red Deer Heating and AC can get out to your system twice a year and do the necessary checks and clean your system, we know we can make your system last longer.
A clean system is a healthy system.
But if you don’t want to hire us to do these checks for you, no problem. Here are some things you can do on your own to help your system out.
We know you heard it before; the “Change your filters as needed”.

Every technician always says that if your filter isn’t perfectly clean, it’s time to change it out.
The filters at your house should come with a cardboard trim around it with some white mesh or fiberglass as the filter media. They’re also the cheapest filter sold at the store. They’re like $7 bucks for a 3-pack.
If that filter isn’t perfectly white, then change it out.
Some people buy these $20-dollar filters. It’s almost like they want to hang on to these filters as long as they can, even though they are brown or gray now. Eww!

That’s the air we are breathing!
That’s the air your children in the house are breathing.
This dirty, dead skin, the pollen-laden filter is now, basically, a contaminated breathing mask essentially for your AC.
If that dirty filter were up against your mouth as you breathed in, you would change it.

Another reason to change that filter is super dirty filters can suffocate the compressor which can cause burnouts, clogged evaporator coils, and other cooling problems.
If the air filter is too dirty, the evaporator coil can even form into a block of ice, really causing some serious cooling issues, including loud screaming compressors that can’t circulate the refrigerant anymore.

Washing the outside AC unit now and then would be nice too.


It doesn’t take much energy to do, and it doesn’t take any soapy solutions to do this either. But if that coil on the outside AC gets clogged as a dirty air filter does, high pressures can occur in the refrigerant system causing loud squeaking noises to arise.
Please don’t use a pressure washer. You will destroy the parts of the system that are crucial for airflow and heat transfer. But you do want to use just enough pressure from the hose to start knocking off loose dirt and small debris down to the ground.

Also, try to focus on not bending any of the fins that surround the AC. These are called the condenser coils.
Well, we hope this has helped you understand where some of those strange, loud noises are coming from on your air conditioner that sits outside.
If you have any questions or doubts that you can isolate the noise, let us know at Red Deer Heating and Air Condition Service – we’d love to help keep your system running for a long time!