When you own a home, there are so many things to worry about. In fact, there are so many things to worry about that it’s easy to focus mostly on urgent matters — appliances that aren’t working, things that are broken or that need repair.

But here’s a secret: Preventative maintenance is the best way to keep your house moving forward at full throttle. That’s especially true of your air conditioning unit, which may be the most expensive appliance in your home — with replacement costs that can run from $5,000 to more than $10,000.

You probably already know this, but: Regularly changing your air conditioner filter is the easiest (and one of the best) maintenance tasks you can do on your own. You may be wondering, though: How often should I change my AC filter? It’s a great question. And we’re here with answers.


AC Filter Change Frequency

Here’s the easy answer: Change your air conditioning filter once every 3 months. That’s once a season. Also, you can check your AC unit, which should indicate (on the unit itself or in an instruction manual) how often the manufacturer recommends changing filters.

Here’s what I do:

I order an inexpensive bundle of AC filters, typically a 6-pack that includes filters my size — 20 x 16 x 1 inches. If you don’t know what size filter you need, you should be able to find the dimensions somewhere on the door to your filter. You can pay a lot of money per filter, or you can save a few bucks. In my experience, you don’t get a lot more use out of a filter by paying more, and expensive filters don’t seem to capture a lot more dust, pollen and dander than an inexpensive filter. So I usually go for a low-priced bundle, like this 6-pack from Nordic Pure (also pictured here).

Also, set calendar reminders for yourself. I use a Google calendar to set reminders for once-quarterly AC filter changes, and I never have to think about it. I get the calendar reminder, I go to the AC closet, and I grab one of the filters from the bundle that sits right inside the door. When I’m down to 1 filter, I order another pack. It makes everything easy.


How to Install AC Filter

This is really the easy part. Find your AC closet and open it. There should be some sort of panel or door that encloses the filter. Find it and open it. At most, there might be some sort of screw that fastens the door shut, but most often the screw is one that can be twisted off using just your fingers.

As you pull out your filter, look for arrows around its edges. These arrows indicate which way the air flows into your unit. Remove the existing filter, set it aside, and then insert the new filter — again making sure the airflow arrows are pointed the same direction, which should be the direction of air flowing into your unit.

You’ll want to remove the old filter from your house, taking it straight out to a garbage can. It should be full of pollen, allergens, dander and other particles you don’t want in your home, so get them out of there as quickly as possible.

And that’s it. You’d done. Just wait 3 months and repeat.


What Does a Filter Do Anyway?

Running an AC without a filter is a terrible idea, which you can probably guess. But so too is running an AC with a filter that’s old and full.

See, air conditioning filters are what prevent miniscule specs of pet dander, dust and allergens from entering into your air conditioner’s return portal. If those particles make it into your AC unit, they will be redistributed through the ducts, where they will get trapped and linger. If you suffer from allergies, this would be a nightmare.

Also, an AC filter needs to be clean to promote smooth air flow. Without it, your home could cool unevenly or your AC unit might be at risk of freezing up, which is certainly no fun to deal with.

Also, the more pet dander and more allergens that are present in your home, the faster your unit’s filter will fill up. If you notice that your filters are exceedingly dirty, even after just 3 months of use, consider changing them out every other month or even once a month.


Where to Buy AC Filters?

Like I said: I prefer getting a bulk pack via Amazon. They show up right at my front door, and I don’t have to worry about finding a replacement filter when I need one. But I also see filters in my unit’s size at the hardware store and even the grocery store.

You’re far more likely to find AC filters in person if you have a common size. It not, it’s an even better idea to order on time. Just remember to keep changing them out regularly. If you do nothing else, make sure to set those calendar reminders, and make sure to change your filter at least once every 3 months.

Thoughts or questions on how often should AC filters be changed? Use the comments section below, or you can also message me directly using our contact page.