AC Setting When on Vacation in Florida: What to Choose

The best AC setting when on vacation in Florida is a few degrees warmer than you normally keep the house, with the system still running and the fan set to AUTO. Turning the AC off saves the most energy on paper, but in Broward and Palm Beach counties the humidity that builds up inside a closed house can cost you far more than the savings.

The goal while you’re away is not comfort. It is keeping indoor humidity in check so mold, musty smells and swollen wood don’t set in.

The Right AC Setting When on Vacation in Florida

For most homes, a setting in the upper 70s to around 80 degrees is a sensible range for a trip of a week or more. Your own number depends on a few things:

• How well the house holds cool air. Insulation, window quality and shade all matter.
• How much sun the house gets. A west-facing home with little shade heats up faster.
• How humid the season is. Summer and early fall demand a lower setting than winter.
• What’s inside. Hardwood floors, instruments, leather, books and artwork are more sensitive to moisture than tile and bare walls.

If you want a starting point, pick a setting about three to five degrees above your everyday one. If you normally keep the house at 74, try the upper 70s. If you normally keep it at 78, go up only a degree or two. In humid months, don’t set it higher than about 80 to 82 degrees, whatever your everyday number is. The warmer the house, the less moisture your system removes, and the longer it has to run to catch up when you return.

For everyday settings, see the article on the best thermostat setting for a Florida summer.

Why You Shouldn’t Turn the AC Off

An air conditioner does two jobs: it cools the air and it pulls moisture out of it. When the system is off in a sealed Florida house, outdoor humidity works its way in through small gaps, and the moisture has nowhere to go.

The EPA suggests keeping indoor humidity roughly between 30 and 50 percent, and no higher than 60 percent, because mold grows more easily as humidity climbs. A house left without air conditioning for a week or two in warm weather can pass that mark easily.

Here is what that can look like when you get home:

• A musty or sour smell in closets, bathrooms and the air from the vents
• Condensation on windows or cool surfaces
• Spotting on walls, ceilings or the backs of furniture
• Warped cabinet doors or sticky wood floors
• Mildew on shoes, towels and fabrics

Once mold takes hold, cleanup is much more work than running the AC at a higher setting would have been. If a musty smell returns after you change the filter, have a licensed professional take a look rather than masking it.

Thermostat and Fan Settings, Step by Step

A few quick changes at the thermostat make a real difference.

1. Set the mode to COOL, not OFF and not a mode that lets the system sit idle for long stretches.
2. Raise the temperature a few degrees above your normal setting, staying within the cap described above.
3. Set the fan to AUTO. With the fan on ON, it runs constantly, including after the cooling cycle ends. Moisture collected on the indoor coil can get blown back into the house instead of draining away. AUTO runs the fan only while the system is cooling.
4. Turn off any schedule or “away” feature that lets the temperature climb too high during the day, unless you know what limit it uses.
5. Check for a humidity or dehumidify setting. Some thermostats and systems include one. If yours does, follow the manual. If you aren’t sure how it works, a fixed, moderate temperature is the safer choice.
6. Replace thermostat batteries if your model uses them. A dead thermostat means a system that shuts off while you’re gone.

If you have a smart thermostat, confirm that it’s connected to Wi-Fi before you leave, so you can check in from your phone. A reading that stays steady is reassuring. A temperature that keeps rising is a signal to have someone look at the house.

What to Check Before You Leave

A system that is already struggling is the one most likely to fail while you’re away. A few simple checks can help.

Simple things you can do yourself

• Replace the air filter. A clogged filter restricts airflow and can contribute to problems like a frozen coil. A Florida filter schedule can help you decide when yours is due.
• Look at the drain opening. If you can see the condensate drain line opening near the indoor unit, make sure it isn’t visibly blocked or full of debris. Don’t take anything apart.
• Keep the outdoor unit clear. Remove leaves, toys, bins and anything leaning against it, and keep plants trimmed back from the sides and top.
• Run the system before you go. Let it cool the house for a full cycle the day before you leave. Check that air comes out of the vents, the house cools down, and you don’t hear unusual noises or see water around the indoor unit.
• Look for water or ice. Water around the indoor unit or ice on the lines needs attention before you leave. If you see it, turn the AC off at the thermostat and call a professional.

Help the house hold up

• Close blinds and curtains on sun-facing windows to reduce heat gain.
• Leave interior doors open so conditioned air reaches every room, including closets and bathrooms when possible.
• Turn off ceiling fans. They cool people, not empty rooms, and they only add a little heat from the motor.
• Make sure windows and sliding doors are fully closed and latched.
• Ask someone you trust to look in every so often, especially on a long trip. They can confirm the house feels cool and dry and spot a leak early.

Short Trips, Long Absences and Vacant Rentals

A weekend or a few days: You can keep your normal setting or raise it slightly. The savings are small and the humidity risk is low, but don’t turn the system off.

A week or two: This is where the warmer setting, AUTO fan and pre-trip checks pay off most.

A month or more, including seasonal stays: Have a licensed professional look over the system before you leave. A maintenance visit lets an AC technician check how the system is running and catch small issues, like a partly blocked drain or weak airflow, before they turn into leaks or breakdowns in an empty house. Ask someone to check in regularly while you’re gone.

Vacant rentals and between tenants: Treat an empty unit like a vacation home. The AC should keep running at a moderate setting, filters should be fresh, and someone should confirm that the system is working. Empty units in humid weather can develop mold quickly.

Storm season: Power outages can happen while you’re away, and the AC will not be cooling during one. When power returns, some systems restart on their own, but others have built-in delays or lockouts, and a thermostat can lose its settings or go blank. Don’t assume everything came back. Have someone confirm the thermostat is still set to COOL and the system is actually running, or check as soon as you’re home. If it isn’t running, leave breakers alone and call a licensed professional. If you’re traveling during hurricane season, review a hurricane season AC checklist before you go.

When to Call a Professional

Some problems should go to a licensed professional, not a do-it-yourself fix. Call before you leave, or have someone call while you’re away, if you notice:

• The system is not cooling the house, or cools weakly
• Ice on the indoor unit or refrigerant lines
• Water pooling near the indoor unit or dripping from the ceiling
• The system turns on and off repeatedly, or won’t start
• A burning smell, loud banging or grinding noises
• A musty smell that comes back after you change the filter
• A tripped breaker

If a breaker trips, leave it off and call a licensed professional. Anything involving refrigerant, electrical parts, capacitors or opening panels should be handled only by a licensed professional. The same goes for water-sensing switches and other safety devices, which should never be bypassed.

If you come home to a hot, damp house and the AC won’t run, emergency AC repair is the next step. Master Tech Air’s phone line is open 24 hours at (954) 629-9825. While you wait, keep windows and doors closed so humid outdoor air stays out, and avoid adding moisture inside, such as long hot showers or drying laundry indoors. Once the AC is running again, check closets and bathrooms for mold or musty odors.