There’s a specific kind of miserable that Central Florida homeowners know well. The AC is on. The temperature reads 74 degrees. But the house feels sticky and close, like the air itself weighs something. You can’t get comfortable. The windows fog up. Your skin never quite dries off.
That’s not a cooling problem. That’s a humidity problem. And it’s one of the most common complaints we hear from homeowners across Central Florida every summer, because our climate is genuinely extreme in this regard. If your home humidity is too high even with the AC running, there’s a reason for it, and there are real solutions. Here’s what we’ve learned from years of working in these conditions.
Florida Humidity Is Not Like Anywhere Else
Most HVAC systems are designed and rated under standard test conditions. The ASHRAE standard conditions used to rate cooling equipment assume 80 degrees and 50 percent relative humidity. Central Florida in August regularly sees outdoor humidity at 85 to 95 percent. That gap matters enormously.
Your AC removes humidity as a byproduct of cooling. When warm, moist air passes over the cold evaporator coil, moisture condenses on the coil surface and drips away. But the system’s ability to do this depends on how long that air is in contact with the coil. Run the fan too fast, run the system in short on-and-off cycles, or have an oversized system that cools the air quickly and shuts off, and the dehumidification effect is dramatically reduced.
The result is a house that hits the temperature target but still feels like the inside of a greenhouse.
We’ve walked into homes where the thermostat read 73 and the humidity was sitting at 68 percent. The homeowners thought something was broken. In a sense, they were right, but the issue wasn’t the temperature.
The Oversized AC Problem
This surprises a lot of homeowners. Bigger isn’t better.
An oversized AC unit cools your home so fast that it never runs long enough to pull real moisture out of the air. The system kicks on, drops the temperature in 10 or 15 minutes, then shuts off. The thermostat is satisfied, but the humidity barely moved. This is called short cycling, and it’s a serious problem in Florida’s climate.
We see this situation most often in homes where a previous HVAC company installed a unit that was too large for the square footage, sometimes because the salesperson thought bigger meant better, or because they didn’t perform a proper Manual J load calculation before sizing the system. A correctly sized system runs longer, steadier cycles and removes significantly more moisture in the process.
If your system is short cycling and your house is humid, sizing may be the underlying issue. It’s worth having us take a look.
Other Common Causes of Indoor Humidity
Blame the AC first, but don’t stop there. There are several other contributors we check for during a service call.
Duct leaks. If your ductwork is pulling in unconditioned attic air, that air is extremely hot and humid. It enters the supply stream before it can be fully conditioned, adding moisture load back into the living space. Central Florida attics in August can hit 130 to 140 degrees with corresponding sky-high humidity. A duct system with even moderate leakage is a huge dehumidification burden.
Crawl space or slab moisture. In homes with any kind of crawl space or porous slab construction, ground moisture can migrate upward. This is less common in Central Florida’s typical slab-on-grade construction but worth ruling out in older homes or those near bodies of water.
Ventilation habits. If you’re opening windows in the evening to let in the “cool” air, you’re also letting in Florida humidity. Evening air here is still saturated with moisture even when it drops to 78 or 80 degrees. Your AC then has to work extra hard to pull that moisture back out.
Bathroom and kitchen exhaust fans. If these aren’t venting properly to the exterior, that moisture stays inside the home and your AC shoulders the entire burden.
What Healthy Indoor Humidity Actually Looks Like
The target range for indoor relative humidity is 40 to 55 percent. At or below 50 percent, the air feels comfortable even at temperatures in the mid-70s. Above 60 percent, most people start to feel the stickiness regardless of temperature. Above 65 to 70 percent, you’re in territory where mold can begin to grow on surfaces.
A simple indoor hygrometer from any hardware store will tell you exactly where you’re sitting. It’s a $15 to $20 investment and genuinely useful. If you’re consistently above 55 to 60 percent with the AC running, something in the system isn’t performing the way it should.
Our AC maintenance visits include checking system performance factors that directly impact dehumidification, including refrigerant charge, coil condition, and airflow. Low refrigerant, for example, reduces the coil temperature and significantly cuts moisture removal. A dirty evaporator coil has the same effect.
Solutions Worth Considering
If your system is the right size and in good working condition but you’re still struggling with humidity, a whole-home dehumidifier might be the right answer. These units integrate with your existing HVAC system and run independently of the cooling cycle to pull moisture from the air. In Florida’s climate, they can make a genuinely dramatic difference in comfort.
Another option is a variable-speed air handler. Unlike single-speed systems that are either fully on or fully off, variable-speed units can run at lower speeds for extended periods. Longer run times mean more air passes over the coil and more moisture gets removed. It’s one of the reasons we often recommend high-efficiency variable-speed systems for Central Florida homes.
And if duct leakage is the culprit, duct sealing is a surprisingly affordable fix relative to the comfort improvement it delivers.
Humidity is genuinely one of the hardest parts of living comfortably in Central Florida. Your AC does a lot of the work, but it can only do so much if the system isn’t sized right, performing well, or properly matched to our climate. If your home feels muggy and you can’t figure out why, reach out to us at All Star Heating & Cooling. We’ve been solving this exact problem for homeowners across Central Florida, and we know what works here.