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Where Is My Air Conditioner Filter?

Your AC’s air filter is usually found in these 2 places:

1. Return register: This is a grille located on the ceiling or wall, where air enters your HVAC system.

Return air filter grille in an air conditioner

Return vent with grate in place (on the left) and open return vent without the grate where you can see the filter and ductwork (on the right)

2. Air handler: This is the indoor part of your AC system, where your home’s air is actually cooled. It’s generally located in your attic, basement, closet or crawlspace.

Where an air filter is located in a central air conditioner

This air handler has a filter base under the unit

The air filter might be on top, below or on the side of the air handler, depending on what kind of air handler you have. Keep in mind your air filter may fit in a small slot near where the return duct connects with the blower fan, or behind a service door on the back of the air handler. You may need to unscrew the service door to access the air filter.

Can’t find your air filter? Call us at (602) 842-0009 and we’ll help you find where the air filter is on your air handler.

So those are the most common places to find your air filter. Want to know how to replace it? Read on...

How to change your air filter

Now that you’ve found your AC’s filter, follow these basic steps to replace it:

  1. Make sure you have the correct size replacement filter. The size of the filter should be written on the side of the filter itself. If you’re unsure of what size filter you need, contact your AC manufacturer or go to a home improvement store and ask for help (you can bring your old filter as an example).
  2. Carefully remove the old filter.
  3. Wipe down the area around the slot or filter area with a cloth to remove dust.
  4. Fit in the new filter by following the direction of arrows printed on the filter (see image below). The arrows indicate that air is being pulled INTO the register/air handler, so make sure the arrows point INTO the system, not towards the house.
Labels on an air filter

Make sure the arrows on the air filter point AWAY from the house, towards the air handler.

Having trouble replacing your filter? We can help.

Do you notice some issues when you go to change your filter? You may need a professional’s help...

2 problems you might uncover while changing your filter

Sometimes, homeowners discover problems with their air conditioner once they change their air filter.

If you notice these 2 issues, you’ll want to contact a professional to fix them ASAP.

#1: Excessive dust in return ducts

When you take off the return vent grille, do you see a layer of dust inside the air duct?

If so, you may have very dirty ducts. Extremely dirty ducts are usually caused by leaks in the ductwork.

Hole in air duct in a home

An example of leaky ductwork. Leaks pull dust from the attic into the ductwork.

You see, if your ducts are leaky, then dust from unconditioned spaces like attics and walls can easily enter the ducts. Then, this dust is blown into your home when you use your AC, and it often collects around the return vent.

If you notice a lot of dust, contact a professional to:

  1. Clean your ducts
  2. Inspect your ducts for leaks. If they find any leaks or holes, they’ll repair them using mastic sealant or metal tape (in a process called duct sealing).

Don’t be surprised if your home has duct leaks—according to ENERGY STAR, most homes lose about 20–30% of the air that moves through the ducts to leaks, holes or poorly connected ducts.

Want to learn more about duct sealing? Read our blog article, “Why Does My Home Get So Dusty So Fast? [FAQ].”

#2: Water around air handler

If your air filter is located in the attic or basement near the air handler, you may notice water around your air handler.

Water around the air handler likely means you have 1 of these 3 AC issues:

1. A frozen evaporator coil. Located in the air handler, the evaporator coil absorbs moisture from your home’s warm, humid air. But, if there’s low airflow or low refrigerant (the liquid that cools air) in your system, then that moisture can form ice on the coils. When the ice melts, it drips into the drain pan until it overflows, causing pools around the air handler.

An evaporator coil in an air conditioner

An AC evaporator coil

If you see ice on the evaporator coil, or notice 1 of these 4 signs, then you’ll need a professional to help diagnose and fix any low airflow or refrigerant issues.

2. A clogged condensate line. The condensate line is the pipe that collects moisture from the evaporator coil and then directs that water outside. If it’s clogged, it can overflow, which creates pools around your air handler. For steps on how to clear the condensate line yourself, read our article “What Do I Do If My Air Conditioner’s Drain Line is Clogged?” or call a professional to do it for you.

A condensate line in a central air conditioner

An AC’s condensate line. You can test to see if it’s clogged by pouring water in it, then going to to see if it’s draining outside.

3. A leaky drain pan. Your AC’s drain pan catches moisture that drips off your evaporator coil. If the pan rusts out and leaks, water will collect around your air handler.

To replace a bad drain pan, go to the nearest home improvement store and purchase a replacement pan. Not sure which drain pan to get? Just contact a professional or ask the store clerk for help. (Make sure you know your AC’s brand and model before you go to the store.)

Drain pan in a central air conditioner

Drain pan location in air handler

Need help from a Phoenix AC expert?

Contact George Brazil HVAC to schedule an appointment with one of our trusted AC technicians. We’ll help you with any filter questions and we’ll fix any AC issues you may have.