How Often Should You Change Your AC Filter in Florida?

The filter is the cheapest part of your HVAC system and the one that gets ignored the most. In Florida, where the AC runs most of the year, that matters more than it does up north.

The short answer

For a standard 1-inch pleated filter, many filter makers recommend replacement about every 90 days. In a Florida home, treat that as the longest you should go, not the target. Change it sooner if:

• You have pets (especially dogs or cats that shed).
• Someone in the home has allergies or asthma.
• There’s construction or renovation nearby, or you live on a dirt or shell road.
• You have a large home on a single small return, which pulls a lot of air through one filter.

A good habit for Central Florida: look at the filter every month, and replace it when it looks gray and loaded — or at 90 days, whichever comes first.

Thicker media filters (4 or 5 inches) are a different product and usually last longer. Follow the manufacturer’s schedule for those.

Why Florida filters load up faster

A filter catches dust every time air moves through it. In a climate where the system cools for most of the year, it simply runs more hours than a system in a mild climate. More run time means more air through the filter, which means it fills up sooner. The calendar on the box assumes average use; Florida isn’t average.

What happens when a filter stays in too long

A loaded filter restricts airflow. Your blower has to work harder to pull air through it, and less air crosses the coil. That can mean:

• Weaker airflow at the registers and rooms that don’t cool well.
• Longer run times, which shows up on your power bill.
• A colder coil, which in bad cases can freeze up.
• Dust bypassing the filter once it’s overloaded or bowed, ending up on the coil and in the ducts.

If you’ve ever had a tech check your delta T and find it out of range, a choked filter is one of the first things to rule out.

Pleated vs. flat fiberglass filters

The cheap blue or green fiberglass filters mostly stop large particles to protect the equipment. Pleated filters fold far more filter media into the same frame, so they catch finer dust while still letting air through. For most homes, a pleated filter in the MERV 8 to 11 range is a sensible everyday choice. We explain the numbers in MERV ratings explained.

How to install a filter correctly

• Match the size exactly. It’s printed on the frame (for example, 20x25x1). A filter that’s even slightly small lets air bypass around the edges.
• Point the arrow toward the blower — the direction air flows. At a ceiling or wall return grille, that usually means the arrow points into the grille, toward the unit.
• Check for multiple filters. Many Florida homes have more than one return. Every one of them needs a filter.

Let us handle it

If you’d rather not hunt for sizes or climb a ladder to a ceiling return, B&I Testing installs pleated filters for $19.99 plus $15.99 per filter — so two filters come to $51.97. You can add it to a duct sanitization visit or book it on its own.

Signs your filter needs changing now

Don’t wait for the calendar if you notice:

• The filter surface looks gray or dark instead of white or off-white.
• Dust building up around the return grille or on furniture faster than usual.
• Weaker airflow from the vents.
• The AC running longer than it used to on similar days.
• A musty smell from the vents — a fresh filter plus duct sanitizing is the usual fix.

How to find your filter size

The size is printed on the edge of the filter frame, written as width x height x depth — for example, 20x25x1. That’s the “nominal” size; the actual filter is slightly smaller so it slides into the slot. Always buy by the printed nominal size.

No old filter to check? Measure the opening and round to the nearest standard size, or let us handle it on a filter installation visit.

How many filters does your home have?

More than you might think. Many Florida homes have:

• A ceiling or wall return grille in the hallway, with the filter right behind it.
• Additional returns in bedrooms or the main living area.
• A filter slot at the air handler itself, in a closet, garage or attic.

Every return with a filter slot needs its own filter, and they’re not always the same size. When we install filters, we check every one.

Serving Ocala and Marion County

We install pleated filters for homes throughout Marion County, including Ocala, Dunnellon, Summerfield and Belleview. See our service area.

Frequently Asked Questions

How often should I change my AC filter in Florida?

Check it monthly and replace a standard 1-inch pleated filter at about 90 days at the most. Homes with pets, allergies or lots of dust usually need it sooner.

What happens if I don’t change my AC filter?

Airflow drops, the system runs longer, rooms may cool poorly, and in bad cases the coil can freeze. An overloaded filter can also let dust bypass onto the coil and into the ducts.

Are pleated filters better than fiberglass?

For most homes, yes. Pleated filters have much more media area and catch finer dust. Fiberglass filters mainly protect the equipment from large particles.

Which way does the arrow on an air filter go?

The arrow points in the direction of airflow — toward the blower and air handler, away from the room.

How much does filter replacement cost?

At B&I Testing, pleated filter replacement is $19.99 for the service plus $15.99 per filter.

Where is my AC filter located?

Usually behind a return grille in a hallway ceiling or wall, or in a slot at the air handler in a closet, garage or attic. Many homes have more than one.