An air conditioner does two jobs. It lowers air temperature, and it removes moisture. Most people only think about the first one, and in Florida the second one is arguably more important — 74°F at 65% relative humidity feels considerably worse than 76°F at 48%.
Why bigger is worse
Dehumidification only happens while the system is actually running. Moisture condenses on the cold evaporator coil and drains away, and that takes sustained runtime — typically fifteen minutes or more before meaningful dehumidification begins.
An oversized system cools the air to the thermostat setpoint in eight minutes and shuts off. It has satisfied temperature without ever getting to the moisture. Do that all day and you end up with a house that is cold, damp, and growing things behind the drywall.
How to tell if this is you
- Cycles are short — under about ten minutes — even on a hot afternoon
- A $15 hygrometer reads above 55% indoor relative humidity
- Condensation appears on windows, vents or toilet cisterns
- A musty smell when the system first starts up
- The house feels clammy despite the thermostat reading low
- Someone previously "upgraded" you to a bigger unit and it got worse
Why it happens so often here
Two reasons. First, a lot of systems are sized from floor area alone — the old one-ton-per-500-square-feet rule of thumb — which ignores insulation, window orientation, ceiling height and infiltration. Second, when a homeowner complains about being hot, the intuitive fix is a bigger unit, and plenty of installers oblige.
Newer construction makes it worse rather than better. A tight, well-insulated 2020s Lake Mary or Horizon West house has a much smaller cooling load than its square footage suggests, so a system sized by the old rule is dramatically oversized.
What actually fixes it
- 1Measure first. Get a hygrometer and log indoor RH for a week before spending anything.
- 2Check the fan setting. Fan set to ON re-evaporates condensate off the coil back into the house between cycles. Set it to AUTO — this is free and fixes a surprising number of cases.
- 3Slow the blower down. Reducing fan speed increases contact time with the coil and improves moisture removal. A technician can do this in minutes on most systems.
- 4Add dedicated dehumidification if the house still holds above 60%. A whole-home dehumidifier is the right answer for tight new construction.
- 5Right-size at replacement. When the system is due anyway, get a proper load calculation and accept the smaller unit it recommends.
If your house is cool and still uncomfortable, do not let anyone sell you more tonnage until someone has actually measured the humidity. We will do that as part of a normal visit — call (407) 777-7241.
Written by
The Orlando AC Repair team — licensed Florida HVAC contractors, #CAC1814992. Everything here comes from work we actually do in Central Florida homes.