How To Change Your AC Furnace Filter

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Table of Contents

At A Glance Steps (Instructions Below)

  1. Locate Filter Locations
  2. Determine Correct Filter Size
  3. Turn Off Ac Unit / Furnace
  4. Remove Old Filter
  5. Insert New Filter
  6. Turn On Ac Unit / Furnace

  1. First, find the locations of all of your air filters. There are several locations you may find an air/furnace filter in your home. You may have an air filter in your air return vents or in your central unit. Your return air vents will be located either on the ceiling or on the wall. To access the filter, unhook the latch and open the hinged screen. Your central unit will be comprised of either an air handler, evaporator, and/or furnace. On your central unit, the filter will usually be behind the access panel, either on the bottom in a tray or where the return duct meets the unit. If you have the owner’s manual for your AC system, it should tell you the location of your filters and the size. If you have a window air conditioner unit, you will also have a filter there to clean.


    Return Air Vent Example

    Ac Air vent

    Central Unit Filter Location Example #1 – filter located where the duct meets the unit.


    AC unit

    Central Unit Filter Location Example #2 – filter located in bottom of unit.


    AC filter location

    Central Unit Filter Location Example #3 – filter located where duct meets the unit.


    Ac unit

    Central Filter Location Example #4 – filter located in bottom of unit.


    ac filter location

    Window Air Conditioner

    Ac dirty filters

  2. Before you buy or change any filter, you need to find out what size you need. Filters come in a wide variety of sizes and you will need to replace the filter with the same size that is in use. Disposable filters come in a cardboard frame and are replaced for the most part on a monthly basis. Most disposable filters display their sizes on the side of the filter in an easy to see place. If the filter does not indicate it’s size, use a tape measure to measure length, width, and thickness. Washable, reusable air filters will come in a sturdy, plastic frame. You will not need to buy a replacement filter if your filter is washable.Filter size on display (check your size specifically, this size is an example only)ac filter number
  3. Turn Off your AC Unit / Furnace at the thermostat. This will prevent the unit from sucking up any debris, dirt, or fittings into the unit. Do not run your unit without a filter.
  4. Before you remove your filter, look for an arrow on the frame. This arrow will indicate which direction the air flow is moving. Make a note of this (you will need to put your new filter with the arrow going in the same direction. Another helpful hint is to write the filter size and the correct air flow direction on the central unit housing for future reference! Remove your old filter. It will be dirty! To minimize the mess, be sure to have a large trash bag handy so you are not trailing dirt, dust throughout the house or on the floor.Airflow marking direction
  5. Insert your new filter with the air flow arrow pointing in the same direction as the old filter. If you are inserting a filter into a return air vent, remember to clean the grill after shutting the hatch.
  6. Turn your AC System / Furnace back on!

Remember to have your system checked twice a year by a licensed professional (once for your AC, once for your furnace).

Call Dial One Johnson Plumbing Cooling and Heating to schedule an AC or Heating Tune Up today!

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