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What Happens If Your AC Filter Is Dirty? Cooling Might Stop Working

What happens if your AC filter is dirty? A dirty filter can cost you extra money & your cooling might even stop working. Here’s everything you need to know about your air conditioner filter.

What Happens If Your AC Filter Is Dirty?

When you’re a homeowner, you have a never ending to-do list of home maintenance jobs, inside and outside the house.

Maintaining your AC Filter is one job you should NEVER forget to do!

The air conditioning filter, or AC filter, in your house may look simple but it’s actually a critical part of your HVAC system.

An AC Filter can extend the life of your HVAC system by keeping it clean, it helps your air conditioner operate more efficiently, and it even plays a part in cleaning the air in your home.

A clean AC filter can even reduce your energy bill AND remove allergens from the air in your home.

In fact, there’s 7 main negatives that can be caused by a dirty air conditioner filter.

What happens if your AC filter is dirty? A dirty filter can cost a lot of money if left too long. Be sure keep that filter clean! HERE'S WHY.
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I’ll go over those below AND answers to common questions about AC Filters.

7 Negatives Caused by a Dirty AC Filter

  1. It can reduce the life of your HVAC System.
  2. A dirty air filter can lead to costly repairs
  3. Your electric bill might increase.
  4. It can increase the level of allergens.
  5. Dust in your air vents.
  6. Your AC might overheat OR freeze.
  7. Your home might not cool to the correct temp.

Here’s a more detailed explanation of all 7 negative effects that might happen if your AC filter is dirty.

A Dirty Filter Shortens the Lifespan of Your AC

If you are running your AC with a dirty filter too often, your AC is running more often and working harder than it should be.

An air conditioner is designed to cycle on and off for short periods. If your air filter is dirty, your AC will have to turn on and off more frequently.

That means your AC will wear out and need to be replaced sooner than it should be.

Increased Need for Repairs

And, a dirty filter can cause dirt to build up inside the air conditioner. That dust and dirt will clog up the parts causing damage to your AC.

And, even if you don’t get dust and dirt inside your AC, your AC is working harder to cool the air when the air filter is dirty.

Your Electric Bill Might Increase

If your AC doesn’t get proper air flow through the filter, the air won’t actually cool as well as it should. Which means your AC will turn on for a cycle more frequently.

If your AC is turning on and off more often than it needs to, that will increase your energy usage. You’ll see that increased energy usage on your electric bill.

Does an Air Conditioner Clean Air?

An air conditioner actually plays an important part in cleaning the air in your home. An air conditioner pulls air from your home, through an AC filter, to cool it.

That AC air filter can remove a good amount of dust, dirt, dander, pet hair, and other allergens from your home. A dirty AC filter can spread dust and allergens through your home.

And a dirty filter can also block air flow in the ducts and through the filter, allowing moisture to build up during hot, humid months.

That moisture can actually cause mold to grow on the filter or inside your HVAC system

No one wants mold in their home. Whether you have mold allergies or not, mold can cause serious health problems.

If you have bad issues with allergies in your home, replace the AC filter often. You can also add a HEPA Air Purifier to improve the air quality even more.

You don’t want all of the dust, dirt, pet hair, and allergens on this filter floating in the air of your home. Check out the highest-rated disposable AC filters on Amazon to have new filters delivered straight to your home. And, check out my DIYs for Cat Owners here. 🙂

Dust and Dirt Builds Up In Your Air Vents

You should never run your AC without an air filter OR with a dirty air filter.

A dirty air filter, or a missing air filter, let’s dust, dirt and allergens build up in the duct work of your home. It can be incredibly hard to get that dirt out of the ducts once it’s in there.

It can be really hard to clean inside of the flexible duct work that’s used in most of my house. Flexible duct work has so many crevices for dirt and dust to settle in.

Your Air Conditioner Could Overheat or Freeze

It’s strange to say that your AC could overheat or freeze from the same cause. But, it’s true. A dirty AC filter can cause your Air Conditioner to overheat or freeze.

If your AC has to turn on and off more often, work harder to cool the air, or has dirty parts while trying to work, this could cause the air conditioner to produce more heat.

Excess heat around your AC will reduce it’s ability to work efficiently or cool your air properly.

Be sure to always follow the manufacturers guidelines for clearance around your air conditioners outside too. Check out my post on how I built DIY removable AC screens for more info on that.

The AC lines could also freeze if it’s unable to push cooled air through the system properly.

Your AC Might Not Cool Correctly

If your AC is running, but the air coming out is warm or the room temperature just never reaches the right temperature then you should check for a dirty AC filter first.

Like I mentioned above, a dirty air filter will reduce your air conditioners efficiency and ability to cool the air.

An air conditioner is designed to come on for a limited time. Then it shuts off for a break before coming on again. If the AC isn’t working efficiently it might not be able to cool the room in the time it would normally take to do it.

If your AC filter is clean, but the AC still isn’t cooling your home, call an HVAC technician.

Here’s a look at my dirty AC filter. You can see all of the dust, dirt, and pet hair clogging this filter. The air wasn’t really able to get through it.

Are AC Filters Necessary?

After reading all of the problems that can be caused by a dirty air filter, I’m sure you know that an clean AC Filter is absolutely necessary.

So, whether you are a home owner, or a renter, you need to know where your AC Filter is located. You might even have more than one.

We have 4 air conditioning filters in our house. HVAC air filters are generally behind a sizable metal or plastic grill, aka an AC Return Air Vent.

If you don’t know where they are, ask your HVAC tech or landlord to show you.

Replacing or cleaning your filter should only take about five minutes every month or two. Add it to your home maintenance calendar, so you never forget.

Or call your landlord, if your filter looks dirty or is making a strange noise.

Here’s a look at a new and clean air filter. This is the same brand of AC filter as the dirty one in the photo above. The air filter in this photo actually has a lower MERV rating than I normally use. I was given this for FREE, so I’m using it. BUT, I normally use one of the filters on this list of the Best AC Filter Replacement for Cleaner Air in a Home.

Now that I’ve covered what happens if your AC filter is dirty, let’s go over some answers to the most common questions about AC filters.

How to Fix a Loud AC Return Vent

If your AC Return Vent is normally pretty quite, but now it’s getting loud or noisy, check your filter!

A dirty AC filter can cause a loud “wind” or even a squealing noise in your air return vent.

Watch this video to see how to fix a loud AC return vent. You can hear in the beginning of the video just how loud my AC vent sounded.

Then, at the end, when I removed the dirty air filter, the noise from the AC vent disappeared.

YIKES! Here's How to Fix a Loud AC Return Vent - AKA The Noisy Air Vent!

How Long Do Air Conditioner Filters Last

Most disposable air filters last between 30 and 90 days. Check your air filter for the recommendations for how often to replace the air filter.

Some homes might need to replace their air filters more often than the recommended guidelines.

If you have pets, live in an area with poor air quality, smoke, have bad allergies, have carpeting, or if have a lot of people living in your home you probably need to replace your air filter more often.

Check out Amazon’s highest rated air filters here, for affordable options you can have delivered to your house.

How Do I Know If My AC Filter Is Dirty

To find out if your air filter is dirty, open the vent door and have a look. If it looks obviously dusty and dirty, you should replace your AC filter.

There are also some less obvious signs that your AC filter is dirty.

  • If your home is dustier around the air vents, you might need to replace your filter.
  • Like I mentioned in the video above, if your air filter is louder than normal, it’s probably dirty.
  • If someone in your home is having allergy problems indoors, you might need a new AC filter. Allergen Air Filters are the best at removing allergens and cleaning the air in a home.
  • Your Air Conditioner is hotter than normal (overheating).
  • Or, your Air Conditioner lines are freezing.
Here I am vacuuming the grill, aka Return Air Vent Cover. Most disposable AC filters can’t be vacuumed clean. Dirt, allergens, dander, and dust will stay trapped in the filter. And, vacuuming the filter risks damaging the exact spacing and thickness needed for proper air flow and protection.

Can I Vacuum My AC Filter

No, you can’t vacuum a disposable air filter. A vacuum wouldn’t be able to remove all of the dirt, dust, and allergens stuck between the fibers on the air filter.

A vacuum might also damage the air filter. The shape and spacing on the air filter is critical to it working effectively. So, it needs to be handled with care.

When you are changing the air filter, you can vacuum behind the air filter, around the frame, and the return air grill or vent cover.

There are some washable air filters that can be reused for a certain period of time. Those washable AC filters can vacuumed before cleaning, per instructions on the filter.

Electrostatic air filters are often washable. Be sure to read the reviews and description when picking a washable air filter.

When you change your Air Filter, vacuum inside the return air vent to keep your HVAC system clean.

Can I Run My AC without a Filter

No, you can’t run your AC without a filter. If you do, your AC will be pulling dirt, dust, hair, and allergens into your HVAC system.

Running your AC without a filter can reduce the lifespan of your HVAC system, cause costly repairs, or deposit dirt in the duct work.

Leave your dirty AC filter in place until you have a clean filter ready to replace it.

Read Best AC Filter Replacement for Cleaner Air in a Home for everything you need to know about MERV ratings for AC filters and how to pick a filter that is safe for your HVAC system AND which filters clean air the best.

Well, that’s it for What Happens if your AC Filter is Dirty!

What happens if your AC filter is dirty? A dirty filter can cost a lot of money if left too long. Be sure keep that filter clean! HERE'S WHY.
What Happens When Your AC Filter Is Dirty? Read this AC Filter 101 for everything you need to know.

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Feeling inspired? Now that you know what happens if your AC filter is dirty, go change that air filter! Have fun and let me know if you have questions.

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