6 Tips to Find Your Hidden Furnace Filter Within Minutes


Have you been searching high and low for your furnace filter but cannot find it anywhere? Then take a look at the 6 tips in this article that will help you find that furnace filter.

You should find your furnace filter in one of these places

  • In front of the fan
  • Inside a duct opening
  • In or behind the return air grill opening
  • Between the return duct and the air handler
  • In the basement, attic, or the back of a closet
  • In the ceiling or wall

Reading that list of possible locations might make you feel like you’re looking for a needle in a haystack. But finding your furnace filter is a lot simpler than it seems. Take a look at the following tips that will help you find yours in a jiffy.

6 Places You Can Find Your Furnace Filter

So it’s time for you to change your furnace filter but you cannot find it anywhere. Now instead of spending the afternoon on a wild goose chase, let’s take a closer look at 6 places you can be sure to find yours.

#1 In Front of the Fan

One of the most common places where you can find your furnace filter is upstream of the fan. Manufacturers put the filter near the fan to stop any kind of debris from entering it. The furnace filter usually covers the way to the fan to prevent any blockages.

#2 Inside a Duct Opening

Do you have an older heating system in your home? Then it is common for older systems to have the air filter located inside a duct opening. If this is the case, it will normally be upstream of the air handler. Furnace filters are often installed inside duct openings in order to keep them out of sight.

Air filter inside duct opening
It’s common for older systems to have the filter inside of a duct opening

#3 In or Behind the Return Air Grill Opening

You can also find your furnace filter at the return air grill. Or, it may be located behind the return air grill opening. Once you have located the grill, check the area thoroughly for the filter.

So, how can you check if your filter is behind an air grill? It’s simple. Follow these steps.

  1. Use a screwdriver to remove the screws around the grill. A new version may have two levers or latches you can pull instead.
  2. Remove the grill cover
  3. Reach inside and pull out the air filter
filter behind an air grill
Your filter might be behind an air grill

#4 Between the Return Duct and the Air Handler

Have you checked all the places we’ve mentioned so far but still cannot find your air filter? Then you should try looking between the return duct and the air handler.

Ok, but what is the air handler?

The air handler is a large metal box. This is the box that houses the fan and its motor. So once you have located the air handler, you should be able to work your way back to the air filter. You can do this by going through the following steps.

  1. Locate the grill opening that pulls air into it. This grill opening is the return duct.
  2. Find the air handler
  3. Work your way from the air handler to the grill opening. The air filter should be located between the two. More precisely speaking, it should be where the return duct and the air handler meet.

#5 ‍A Basement, Attic, or the Back of a Closet

Is looking into ducts, air handlers, and grill openings not working out? Then you may have to expand your search. That is, you may have to check the extremities of your home to find the filter. You might be able to find yours in a basement, attic, or at the back of a closet.

So, what should you look for in these locations?

You are looking for the air handler or the furnace itself as the air filter is often right next to them. Your furnace and air handler are most likely located in the basement, attic, or inside a closet. Once you are in the right place, here’s what you can do.

  1. Look in the attic, basement, or the back of a closet for a slot the size of an air filter. It should be next to the air handler. The space for your air filter could look like any of the following
    1. A slot about 1* inch wide
    2. A hinged cover
    3. A removable cover
      1. *NOTE: Your air filter’s slot may be over 4 inches wide depending on the make and model of your furnace
  2. Reach into the slot or remove the cover. Your new filter should match the size of the old filter
air filter beside the furnace
The air filter could be beside the furnace

#6 In the Ceiling or Wall

To conclude our scavenger hunt here is the last place you can look for your furnace’s filter. That is in the ceiling or on a wall. When looking for an air filter in these places, keep your eyes peeled for the following.

  • An air return duct
  • A slot the same width as your air filter
  • A hinged cover
  • A removable cover
Air filter in ceiling
You may find the air filter in the ceiling

Do All Furnaces Have a Filter?

Now, I know what you’re thinking.

Is it possible that you are searching for something that simply does not exist? Do all furnaces have a filter?

The short answer to this question is yes, all furnaces have a filter in order for them to work properly. But if you are struggling to find yours, then your furnace may not have a filter. Here are a couple of reasons why it might not.

What if this is the case with your furnace? Then you should get an HVAC specialist in to check the furnace immediately. The specialist will be able to do the following.

  • Check that everything is still safe
  • Install a filter to improve the airflow and efficiency of the furnace
  • Prevent a carbon monoxide leak or fire

If You Still Can’t Find the Filter

You’ve searched everywhere for the air filter but haven’t found it. Your filter seems to be playing (and winning) the hardest game of hide-and-seek known to man. Now you’re feeling really frustrated and are ready to throw in the towel. What can you do?

Do not panic, because you can call your furnace supplier or an HVAC professional to find the filter for you. Here are some of the benefits of calling an HVAC professional to check out and find your furnace filter.

  • An HVAC professional will help you to locate your air filter quickly
  • They will tell you which air filter size and width is best for your system
  • They can change your furnace’s air filter for you
  • An HVAC service technician can recommend the best maintenance plan for your furnace. They base this plan on the design of your home. This includes the replacement frequency of your filter and whether it would be best to use a reusable one.
technician changing filter
If you still cannot find the filter, call an HVAC service technician


I hope we’ve managed to help you find your furnace today!

If we have, make sure to check out our other furnace guides to learn how to lower your energy bills AND make your furnace last longer.

Are you still stuck? Please get in touch via our contact form or by leaving a comment below.

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I've been helping homeowners with appliance repair since 2016. Starting out as an enthusiastic amateur, I've since worked with many Appliance, HVAC, and DIY experts over the last 7+ years. My mission is to help fix your appliances and prevent future issues - saving you stress, time, and money. Visit my author page to learn more! Read more