The thermostat reads the right temperature, but the house feels damp. Surfaces are clammy. The air feels heavy. You keep lowering the thermostat to get comfortable, which makes the house cold but still humid.
In Florida, your AC is a dehumidifier as much as it is a cooling system. When warm, humid air passes over the cold evaporator coil, moisture condenses on the coil and drains away. A properly working AC in a properly sealed house should hold indoor humidity between 45 and 55 percent.
If it is not doing that, one of these things is happening.
The system is oversized
This is the most common cause of a humid house with a working AC, and the hardest to accept because it means the system is too powerful, not too weak.
An oversized system cools the air quickly. The thermostat reaches the set temperature in a short cycle — five to eight minutes instead of 15 to 20. The compressor shuts off. But the coil was not running long enough to pull significant moisture out of the air. The temperature is right. The humidity is not.
Short run times mean less condensation. Less condensation means the humidity stays high. The fix for an oversized system is not a repair — it is a proper load calculation and, eventually, a right-sized replacement.
The fan is set to "on" instead of "auto"
When the fan runs continuously, it blows air across the wet evaporator coil between cooling cycles. The moisture that condensed on the coil during the last cycle gets re-evaporated and pushed back into the house. The system removes humidity during the cooling cycle and returns it during the fan-only cycle. Set the fan to "auto."
Duct leaks
If the return duct has leaks in the attic, the system pulls hot, humid attic air into the air handler and mixes it with house air. The AC works harder, run times increase, and indoor humidity stays elevated because the system is constantly fighting new moisture infiltration from the attic. Sealing the return duct is the fix.
Dirty evaporator coil
A layer of grime on the coil reduces its surface contact with the air. Less contact means less moisture removal. The system still cools the air, but dehumidification drops. Professional coil cleaning restores performance.
Building envelope leaks
If the house has air leaks around windows, doors, recessed lights, plumbing penetrations, or the attic hatch, humid outdoor air infiltrates constantly. The AC removes moisture, and more moisture enters behind it. Sealing the envelope is outside HVAC scope, but it directly affects HVAC performance.
What to do
Check the fan setting first — switching to "auto" is instant and free. Replace the filter. If humidity stays above 55 percent with a clean filter and the fan on auto, the cause is likely oversizing, duct leaks, or coil condition. A technician can measure airflow, check static pressure, and assess whether the system is cycling correctly.
Call (727) 477-3256. If you have a hygrometer or a smart thermostat that reads humidity, tell us the number when you call.