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Why Is Your Air conditioner Making Noise When Off? 6 Possibilities

Why Is Your Air conditioner Making Noise When Off? 6 Possibilities

What if your air conditioner explodes on you? There is nothing as scary as a noisy air conditioner, especially if the noise is a loud “pop” or “bang”. 

Now, don’t worry, air conditioners rarely explode, however, air conditioners making noises when off is usually a sign that something is wrong. Modern air conditioners are supposed to work silently. 

Sometimes it can even be confusing if your air conditioner seems to be in perfect working condition. 

There are two ways to go about this: If the noise is coming from the inside or outside of your home. 

Noise Originating From Inside Your Home

There are a couple of components we’ll be going over as we try to troubleshoot this frightening problem.

1. The Filter(s)

Sometimes, the cause is an overly restrictive air filter. Filters are usually located behind your vents’ supply valve. In the case of an overly-restrictive filter, air conditioners make a loud bang when turned off.

When you first turn on your air conditioner, the air is first sucked into the system through the supply vents. This suction force causes the filter to be sucked onto the supply vents lid and gets held there. 

When you switch off your air conditioner, the suction force is turned off, and the filter freely falls. 

Restrictive air filter? These filters have small holes (10+ MERV rating). Even though these filters are more efficient, they get clogged very easily and start restricting your air conditioner’s airflow. As a result, your air conditioner increases its suction force as it struggles to take in more air- this it ends up sucking the filter onto the supply vent. 

The other way your basic (no restrictive) filter might be causing this sound is if it’s clogged with dirt and debris.

Here is how you can beat a noisy filter:

  • Replace your restrictive air conditioner with a basic but thicker one.
  • Clean it if it’s a basic filter. We advise you to clean your filter once every other month.

If you live in Phoenix, Arizona, and can’t perform these tasks on your own, American Home Water and Air can lend a hand. Read about them here.

2. Broken dampers 

Dampers are mechanical vales found inside your air conditioner vents. 

Dampers are responsible for regulating the amount of air supplied to each room. Due to age, some of these dampers become faulty and end up producing a lot of noise- This explains why your air conditioner makes a loud noise when turning off. 

In this case, there isn’t much you can do apart from calling an HVAC technician (You might have to get your dampers fixed or replaced).

3. Noisy ducts

As you might have noticed, the majority of air conditioner ducts out there are made of steel metal. Steel has a habit of expanding and contracting when heated or cooled (This time around, it’s a “crackling” sound instead of a loud “bang”).

Your ducts might be behaving this way because they’ve become weak over the years. If your air conditioning system is relatively new, then the metal sheets might be poorly reinforced or too big or small for the amount of air passing through it. 

4. Faulty fan

Squeaky or lose fans are not a rare spectacle with slightly old air conditioning units. However, you might have to take a look at the blower wheel for any serious damage. If the fan is loose, a sudden change in airflow will knock it off balance and slam it against its housing. 

Faulty fan

Noise Originating From Outside

There are only two components you should be suspicious of: The fan and compressor unit.

Compressor Unit

The compressor unit is the main component of the cooling system. It’s like the heart of your air conditioner that is responsible for pumping the refrigerant. Now, inside the compressor unit, there are several other components. 

Among those components are several pumps that do the actual pumping. These pumps are usually fixed on support springs that sometimes get loose (this is why you’re advised to schedule for at least one air conditioner maintenance a year). 

If one of the support springs is loose, the pump will lose balance and wobbly. Now, you might not hear any noises when your air conditioner is running because the vibrations make it stable. However, when you turn off your air conditioner, the vibrations cease, and the pump suddenly becomes unstable creating a “bang” sound in the process. 

Note: There isn’t much you can do to fix this problem. The only way is to replace your entire compressor unit (Yes, there are no spare parts for this one). Of course, it’s significantly costly. We’d recommend it to leave it as it is if you’re not under warranty (It’s not a sound you should be worried about- Your air conditioner will not fail).

6. Faulty fan

A faulty fan is another possibility you should look into if your air conditioner makes noises when turned off. There is another fan in the outside unit that can become faulty and create some noises. Get a technician to see if it’s loose or damaged.

“Red Alert” Air Conditioner Sounds You Should Be Wary About

Screams

Screams are one of those “red alert” sounds you should always be on the lookout for. A screaming air conditioner is usually a sign of a refrigerant leak. Refrigerant leaks will not only freeze your air conditioner, but they’ll also threaten your health. 

Turn off your air conditioner and call your technician immediately!

Clicks

Clicks are usually a sign that something is wrong with one of your air conditioner’s electrical components (It could a short circuit). Small as they are, short circuits get worse over time and can even kill your air conditioner.

You should now be able to tell why your air conditioner makes loud noises when turning off. 

Always remember to call your technician if you’re in doubt.

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