Can you put a filter in a window air conditioner?

With summer heat in full force, many homeowners look for ways to stay cool while also saving on energy costs. Window air conditioners are an affordable and easy option for cooling one room, but their filters can quickly get clogged with dust, pollen and other particles. This reduces airflow and efficiency. So an important question arises: can you put a filter in a window air conditioner to improve its performance?

How Window AC Units Work

To understand if you can add a filter, it helps to first look at how window air conditioners work. Window ACs are self-contained units that sit in a window frame. They pull air from the room over evaporator coils that contain refrigerant. As the warm air passes over the cold coils, it cools down. The refrigerant absorbs heat from the air and gets pumped outside to the condenser coils where it releases the heat.

The now cooled air gets blown back into the room via a fan and vent. This constant cycling of room air over the evaporator coils produces the cooling effect. At the same time, the unit pulls in outside air over the condenser to discharge the collected heat.

The Role of Filters

Now in this air circulation system, filters play a key role. They are meant to trap dust, pollen, pet dander and other particles so they don’t clog up the internal coils and fans. If the coils get coated in debris, it will reduce airflow and cooling capacity. Filters keep the sensitive internal components clean for optimal performance.

Can You Add a Filter?

So can you put an aftermarket filter into a window AC unit that didn’t come with one? The short answer is yes, you can add a filter to most window air conditioners. However, there are some important considerations to keep in mind.

Filter Types

If your window AC did not come with a filter, you will need to purchase an appropriate aftermarket filter. There are a few common types:

• Reusable foam filters – Made of polyurethane foam that can be washed and reused.
• Fiberglass filters – Disposable filters made of fiberglass that trap particles.
• Pleated filters – Feature many pleats for increased surface area to capture particles.
• Electrostatic filters – Have an electrostatic charge to attract and grab particles.

For window ACs, reusable foam or pleated filters are common options. Make sure to get the right size filter that will fit your unit.

Accessing the Filter Slot

Window air conditioners are designed to be self-contained and usually do not come with filter access panels. This means you likely will need to DIY a way to open the unit and insert a filter. Here are some options:

• Cut or drill a hole in the plastic housing to slide filters in and out. Make sure not to damage internal components.
• Remove the front plastic panel for access. You will need to fashion a way to securely reattach it.
• Slide the filter in sideways through the front vent openings. This may limit filter size.

Be very careful when modifying the unit’s plastic housing so you don’t impact the air sealing. Any air gaps could reduce cooling capacity. Also take care not to obstruct internal fan blades with the filter.

Maintenance

Once added, the filter will need occasional cleaning or replacement. A dirty, clogged filter will quickly reduce performance. Here are some filter maintenance tips:

• Check the filter at least monthly during heavy use seasons.
• Change disposable pleated filters 2-3 times per year.
• Clean reusable filters by vacuuming or washing with mild detergent.
• Make sure filters are completely dry before reinstalling.

Expert Recommendations

Most HVAC experts agree that adding a filter to a window AC unit that doesn’t have one can improve efficiency and extend the operating life. However, they recommend exercising caution.

“Improper filter installation that allows air leakage or obstructs airflow could actually lower performance and damage the unit. My advice is to thoroughly research your specific model to determine the best way to add a filter,” says James Reynolds, owner of Reynolds Heating and Air Conditioning.

“If you’re not able to properly fashion a way to securely insert and remove a filter, it’s best to stick to the manufacturer’s original design. You can always upgrade to a newer window AC with built-in filter access,” advises Kyle Henderson, manager of Arctic Cool HVAC.

Conclusion

Adding a filter to a window air conditioner that didn’t originally come with one can provide benefits, but also comes with some risks. With careful installation that doesn’t compromise the housing or internal airflow, and proper ongoing maintenance, an aftermarket filter can capture dust and allergens for better performance. However, improperly adding a filter can actually lower cooling capacity and damage the AC. Consulting an HVAC professional is advised to determine if a filter addition is appropriate for your specific model and setup.

Frequently Asked Questions

Can I just tape a filter to the back of a window AC?

It is not recommended to tape or adhere a filter to the exterior of a window AC unit. This can restrict airflow into the unit and lower its cooling capacity. The proper method is to insert a filter into the unit’s existing air flow path, usually just behind the front vent. Great care must be taken not to obstruct the internal fan.

Do all window ACs have filters?

Not all window air conditioners have internal filters. Older, lower-end models often lack filters, relying solely on the fins of the cooling coils to capture some particles in the airflow. Higher-end modern units will typically include a mesh filter behind a removable panel to keep the coils cleaner for better efficiency and performance.

Should I clean or replace AC filters?

It depends on the filter type. Reusable filters made of foam or mesh can be cleaned and reused many times. Rinsing with water and mild detergent is recommended. Disposable pleated filters need to be replaced typically 2-3 times per year. Electrostatic filters may only need annual replacement. Always check your owner’s manual.

Where should the filter go in a window AC unit?

Window AC filters are typically placed just behind the front vent intake grille at the point where air is pulled in and passes over the evaporator coils. This allows it to filter particles before they reach the sensitive internal components. The key is ensuring unobstructed airflow through the filter’s positioning.

How often should I change my window AC filter?

Most manufacturers recommend changing window AC filters at least every 2-3 months during the peak summer cooling season. If you have pets or live in a dusty climate, consider monthly filter changes. Check your filter once a month by removing and looking for debris buildup. Change it sooner if it appears clogged.

Can I DIY install a filter in my window AC?

You can DIY install an aftermarket filter in a window AC, but extreme care must be taken. You will need to fashion a way to open the housing and properly insert the filter without restricting airflow or letting air escape. Professional installation is recommended for most homeowners.

Will adding a filter reduce my window AC cooling?

Adding the correct size, style filter and installing it properly should not noticeably reduce cooling capacity. In fact, it will maintain optimal airflow. An oversized, improperly installed filter that obstructs airflow would lower performance. Routine maintenance is key.

How do I know if my window AC filter needs replacement?

Check your window AC filter about once a month during use. Pull the filter out and inspect for accumulated dirt and debris. Hold it up to the light to see if densely packed particles appear. If it is visibly clogged or it has been 3 months, replacement is likely needed for optimal performance.

Adding a Filter to Different Window AC Brands

The best method for adding a filter can vary based on specific window air conditioner models and brands. Here are some tips for common brands:

Frigidaire

• Remove front grille and slide filter into slots behind
• May need to cut housing on older models
• Reusable mesh or pleated filters recommended
• Change every 1-2 months

GE

• No front panel access on most models
• Must cut or drill hole in housing to insert filter
• Electrostatic filters provide the best performance
• Inspect filters monthly, replace as needed

LG

• Mesh filter slides out from front for cleaning
• Reusable foam filters can also be inserted from front
• Rinse filters under tap monthly during use
• Replace foam filters annually

Whirlpool

• Entry-level models lack filters
• Newer models have washable mesh filters behind front grille
• Cut housing on old units to insert third-party filter
• Inspect and clean mesh filters monthly

Friedrich

• Front or rear panel access to slide in pleated filter
• Wash foam filters monthly in warm water with detergent
• Replace pleated filters every 2-3 months
• Avoid oversized filters blocking airflow

Always consult your owner’s manual for the best guidance on maintaining filters in your specific window AC unit and model.

Window AC Filter Sizes

AC BTU Rating	Filter Size Needed
5000 – 6000 BTU	11 x 13 x 1 inch
6000 – 8000 BTU	12 x 14 x 1 inch
8000 – 10,000 BTU	14 x 16 x 1 inch
10,000 – 12,000 BTU	16 x 20 x 1 inch
12,000 – 18,000 BTU	20 x 20 x 1 inch
18,000 – 24,000 BTU	20 x 24 x 1 inch

When selecting a universal replacement filter, match it to the air conditioner’s BTU rating. Standard sizes are available between 11×13 inches up to 20×24 inches. Measure the existing filter or internal filter slot to ensure a proper fit.

Conclusion

Adding a filter to a window air conditioner can certainly provide benefits in terms of enhanced performance and longevity. But it must be done properly so as not to disrupt airflow or cooling capacity. With careful planning, the right filter size and type, and routine maintenance, an aftermarket filter can help keep your AC coil free of dust and debris. Just be sure to evaluate your particular model and installation configuration before modifying the unit. Professional help is recommended when in doubt. Stay cool!