Eight AC maintenance tips that get a Florida system through August.

The filter is the cheapest part of the system, and it protects the most expensive ones. Air passes through it on the way to the evaporator coil, the cold coil inside your indoor unit that pulls heat and moisture out of the house. A clogged filter starves that coil of air. The system runs longer, the bill climbs, and in a bad case the coil freezes over.

Pull the filter once a month and hold it up to a light. If it looks gray or you cannot see through it, change it. Our air filter guide for Florida homes covers sizes, the airflow arrow and MERV, the rating for how fine a dust a filter catches.

Your AC pulls water out of the air as it cools. That water, called condensate, drips into a pan and leaves the house through a small PVC pipe, where algae grows over a summer until it plugs the line.

Once a month from May through October, pour one cup of plain white distilled vinegar into the T fitting access port, the capped opening a few inches down the pipe from your indoor unit. Skip bleach, which is hard on the PVC glue joints and the metal pan. The Florida Building Code requires overflow protection on this drain, such as a float switch that shuts the system off when water backs up. If your AC quits and the closet floor is wet, that switch did its job. Our post on a clogged AC drain line shows how to clear it.

The outdoor unit, called the condenser, is where the heat from your house goes. It can only shed that heat if air moves freely through its thin aluminum fins. Grass clippings, lint and the salt film everyone near the water in Port Richey and Gulf Harbors lives with all pack into them, and salt also corrodes the metal.

Turn the power off at the disconnect, the small box on the wall beside the unit, then rinse the fins with a garden hose on a gentle setting. Never use a pressure washer. Keep two feet clear on every side. Near the Gulf, rinse once a month. Our article on salt air AC damage in Port Richey shows what corrosion looks like.

Leave the fan switch on AUTO, not ON. A fan that runs nonstop blows air across a wet coil after the cooling stops and puts that moisture right back into the house.

The U.S. Department of Energy suggests 78 degrees when you are home and need cooling. In our humidity, a steady setting between 74 and 78 beats chasing a lower one. Setting 68 on a hot afternoon does not make the vents blow colder. It only makes the system run longer. If you leave Florida for the summer, our guide to summer AC settings for snowbirds explains why an empty house should never have its AC shut off.

Here, how damp the air is matters as much as how cold it is. The measure is relative humidity, which compares the moisture in the air with the most it could hold at that temperature. The U.S. Environmental Protection Agency advises keeping indoor humidity below sixty percent, and ideally between thirty and fifty. Above sixty, mold and dust mites move in.

An inexpensive humidity gauge from a hardware store tells you where you stand. A reading above sixty with the AC running often points to the fan left on ON, an oversized system that shuts off too soon to dry the air, or humid air leaking in. Our article on the cold but clammy house explains each one.