How to Clean Central AC Filter | A Step-by-Step Procedure

A dirty air filter can allow dirt, dust, and debris to circulate in the indoor air you breathe and put your health at risk. It can also render the unit energy-inefficient and drive up your electricity bill. 

As a heating, ventilation, and air conditioning (HVAC) technician, I recommend cleaning the air filter once every month if it is reusable. For that reason, you should know how to clean central AC filter on your own.

You will want to replace it every three to six months for a replaceable type, depending on what your user manual recommends.

Cleaning or replacing the filter is essential to maintaining your AC’s performance. Dive in to learn how to go about it. 

What You Need to Clean Your Central AC Filter

Now, we will go into the list of things you need to clean your dirty central AC filter in a moment. But first, here is something we need to get out of the way.

The filter in your ducted reverse cycle air conditioning system can be one of the two main types: disposable or reusable filter.

You will need to consult your AC’s instruction manual to determine whether the filter is disposable or reusable. Typically, AC companies recommend swapping out a disposable air filter at least once every season.

If you have a reusable filter, cleaning it is an option – in which case, here are the things you will need for the exercise.

  • Vacuum
  • Soft-bristled brush
  • Garden hose
  • Mild dish soap or laundry detergent (optional)
  • Screwdriver

How to Clean Central AC Filter (Step-by-Step Procedure)

Cleaning the filters on your central AC unit may sound like a daunting task, but it is not. Here are the simple steps to follow.

Step 1: Turn off the air conditioner

The first thing to do is turn your air conditioning unit off. Allowing the air conditioner to run without the filter will cause a rush of unfiltered air into your home.

The AC’s evaporator coils and other internal parts will collect dirt and other particles in the process. This way, you run the risk of causing irreparable damage to your air conditioning system.

So, do not use air conditioner until you have replaced the filter.

Step 2: Remove the filter

Locate the return air grille and remove the dirty old filter. On these large central air conditioning units, you should find the filter cradled somewhere behind the return air grille or along the length of your AC’s return duct.

You might need to undo a few screws to access it or take it out. The user manual from your manufacturer should provide you with directions on how to access the filter.

When you get that filter out, have a look at it. It will either be a disposable filter or a reusable one.

If you have a replaceable filter on your air conditioner, have a look on the side for a sticker with instructions on it. There will be a step-by-step guide on how to acquire and install a replacement.

For a reusable filter, it should also feature instructions on whether or not you can wash it. Alternatively, you should find this information in your user manual. Pay keen attention to it so you do not risk damaging your AC’s air filter.

Step 3: Vacuum it

Vacuuming should be sufficient for removing much, if not all, of the dirt. Use the brush head attachment on your vacuum cleaner for this part.

The combined power of the vacuum mechanism and the scraping action of the brush should get rid of the dirt, grit, and debris.

Sometimes the grille will be a little dirty too. You don’t want to return a clean air filter onto a dirty grille, so give it a bit of vacuuming with the brush head attachment too.

Vacuuming can sometimes not get all the dirt out; that is where washing comes in. In this part, just focus on sucking out as much dirt as you can.

Step 4: Wash the filter with water and vinegar solution  

Start by reading the instructions printed directly onto the filter or its manual to ascertain if it is washable. Some AC filters are not designed to get wet. Washing such filters would most likely damage them.

For a water-friendly filter, soak it in a mixture of equal parts water and vinegar for about an hour before rinsing it for a deeper clean.

The rinsing should get the job done. However, if you are not satisfied, consider washing it with a sponge or soft-bristled brush dunked in a solution of mild dish soap and water.

Step 5: Hose it down.

You can always get the job done entirely from your sink. However, feel free to take the filter outdoors for some thorough rinsing with your garden hose to remove any cleaning solution or soap residue.

Do not use a pressure washer or pressurized hose nozzle attachment as this might damage the fragile filter.

After finishing this part, allow the filter to dry in a shaded area and then replace it.

Do this frequently depending on your AC type. For example, window AC filters require regular cleaning.

Telltale Signs that your Air Filter Needs Cleaning

AC manufacturers will usually specify the cleaning requirements for their respective filters. These instructions will include the recommended intervals for cleaning the filters – often once every two weeks or once a month. Also, check when to buy a new central air conditioner.

Much as these instructions will tell you what to do and when to do it, your AC filter can always get dirty sooner, depending on the environment and the care and maintenance it gets. 

So, here are some tips to tell you when your air filter may be due for a cleaning.

a)      The air conditioner is doing a poor job cooling your home. 

b)      The air quality in your home is noticeably bad.

c)      Your air filters are evidently unclean.

Final Thoughts

The fact is, accumulated dirt will clog your AC’s air filter, inhibiting airflow and affecting its ability to cool your home.

Thankfully, you now have this guide on how to clean central AC filter at your disposal to walk you through the cleaning process.

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Melanie Mavery is an aspiring HVAC technician who is fascinated by the trends and opportunities in the HVAC industry. She spends most of her day writing content on home improvement topics and outreaching to prospects.  She's always looking for ways to support HVACs!