If you are heading back north for the summer, the next 30 minutes of work on your thermostat and air handler are the most important investment you will make in your Florida home this year. We get the same call every May and June - a snowbird walks back into a closed-up house and finds mold on the baseboards, the furniture, and the back of the framed pictures. It is almost always preventable. Here is the checklist we walk customers through every April.
Why a closed-up Florida house is dangerous
Florida summer outdoor humidity averages 75–85% with daily highs over 90%. Indoor humidity above roughly 60% is where mold spores germinate on porous surfaces - drywall, fabric, leather, paper. A house with the AC turned off in July hits 80% interior humidity within a day. A house with the AC set to a high "vacation" temperature (say, 85°F) is barely better - the system runs so rarely that it never pulls moisture out of the air.
The right setup is not "AC off" or "AC high." It is "AC running enough to dehumidify, but not so often that it runs up the bill." Those two goals are in tension; here is how to balance them.
The thermostat settings that actually protect the house
- Temperature setpoint: 78°F. Higher than this and the system short-cycles or never runs; lower wastes money. 78°F is the comfortable low end of Florida indoor air and produces enough runtime to dehumidify.
- Fan: AUTO, never ON. A fan running with the compressor off re-evaporates moisture from the wet evaporator coil back into the house. This is the single most common mistake we see. Always AUTO when you are away.
- Humidity setpoint: 55%. If your thermostat supports humidity control (Ecobee, Honeywell T10, most communicating systems), set the dehumidify setpoint to 55%. The system will overcool slightly when needed to pull moisture - the right tradeoff for a closed-up house.
- Schedule: disable. A "vacation" schedule that ramps temperature up overnight is a trap; you want consistent setpoint while you are gone. Disable schedules and run a single hold.
Should you add a dedicated dehumidifier?
For larger homes (over roughly 2,500 sq ft) and for any home with a humidity problem already documented, a whole-house dehumidifier (Aprilaire, Santa Fe, Ultra-Aire) is a meaningful upgrade. It runs on its own thermostat, pulls moisture without overcooling, and pays for itself in protected hardwood floors and avoided mold remediation within a few seasons. We install them as a tied-in unit to the existing duct system; cost runs $2,500–$4,500 installed depending on the model and ductwork.
If you have already had a mold issue in the house, this is the upgrade we usually recommend. If you have not, the AC + humidity-aware thermostat combination above is enough for most homes.
Float switch and leak protection: do this before you leave
The other failure mode that ends a snowbird summer badly: the condensate drain clogs while you are away, the float switch is missing or stuck, and the drain pan overflows for weeks before someone notices. By August you have a ceiling on the floor.
- Confirm a working float switch. If you do not have one, install one - $40 part, 30-minute install, prevents tens of thousands in water damage. Code-required on most newer Florida installs and worth retrofitting on older systems.
- Flush the condensate line before you leave - a cup of distilled vinegar, dwell 30 minutes, warm water rinse. Algae will grow whether you are home or not; start the summer clean.
- Add a leak detector in the closet or attic where the air handler lives. Wi-Fi models (Moen Flo, Honeywell Lyric, even basic Govee) text you the moment they sense water. $30–$60.
Power outage and surge planning
Florida loses power. Sometimes for hours, sometimes for days, especially during the named-storm months your house will be sitting empty through. A few choices to make before you leave:
- HVAC surge protector at the disconnect. If you do not already have one, this is the time. Lightning and grid surges during power restoration kill compressors. $150–$300 installed.
- If you have a whole-home generator, schedule its annual service before you leave - and run a load test under cooling load. A generator that started fine in February will not necessarily carry the AC at peak summer load.
- Smart-thermostat alerts. Ecobee, Honeywell, and Sensi all send phone alerts when the system loses power, the temperature spikes, or the AC stops heating/cooling. Connect them and verify alerts arrive at your northern phone before you leave.
Smart monitoring: your eyes on the house
The cheap, modern stack we recommend for snowbird homes:
- Wi-Fi thermostat with humidity reporting (Ecobee Premium and Honeywell T10 both work well).
- Wi-Fi water leak sensors in the air handler closet, under sinks, and behind the washing machine.
- One indoor camera with a wide view of the main living area - the temperature/humidity readout from the thermostat, plus a visible photo, tells you fast if something has gone wrong.
- A trusted local contact who can be at the house in under an hour if an alert hits. We have customers whose neighbors hold a key; we have customers who pay a property manager. Either works. Nobody works.
What we do for snowbird customers
We run a "vacation prep" visit in April and May for customers who are leaving for the summer - tune-up plus float switch verify, condensate flush, and a written summary of the thermostat and humidity settings. We also do mid-summer wellness checks (some customers prefer a tech in the house once a month while they are away; others rely on smart sensors). Either is fine; the worst option is no visibility at all.
Book your pre-departure visit
If you are leaving Punta Gorda, Punta Gorda Isles, Port Charlotte, North Port, or Cape Coral for the summer, the calendar fills up fast in late April and early May. Call (941) 205-6331 or request service and we will get a tech out before your flight.