After more than 20 years managing rental properties in St. Augustine and St. Johns County, I've seen the same HVAC service calls come up again and again. A system that won't cool. An air handler dripping water. Utility bills climbing for no obvious reason. In the vast majority of cases, the fix is simple — and the problem was preventable. This guide covers everything a Florida tenant needs to know to keep their AC running well, their energy bills reasonable, and their relationship with their landlord smooth.
Why Florida Is Different
Most of the country treats the air conditioner as a summer appliance. In Florida, it's infrastructure. From roughly March through November, your AC is running every single day, often for 12 or more hours at a stretch. Even in our mild winter months, the system typically cycles on during warm afternoons. That continuous workload has real consequences: filters clog faster, drain lines accumulate more growth, and wear adds up more quickly than it would in a northern climate.
Florida's humidity compounds the challenge. Your HVAC system doesn't just cool air — it dehumidifies it. That moisture has to go somewhere, and it exits through the condensate drain line. When that line is clear, no problem. When it's blocked, water backs up into the air handler, and that's when you get drips, leaks, and eventually a system shutdown. We'll cover that in detail below.
The bottom line: habits that would be fine for a tenant in Ohio can cause real problems in a Florida rental. A little basic maintenance on your end goes a long way.
The Single Most Important Thing: Change Your Filter
If you do nothing else on this list, change your air filter regularly. This is the tenant's most important HVAC responsibility and the one most commonly neglected.
The filter's job is to catch dust, pet dander, pollen, and other particles before they reach the air handler. When it's clean, air flows freely and the system runs efficiently. When it's clogged, the system has to work harder to pull air through, which increases energy consumption, strains the blower motor, and — critically — can cause the evaporator coil to freeze. A frozen coil means the system stops cooling entirely, and by the time you notice it's warm inside, you may be looking at a service call that a new filter would have prevented.
In Florida, a filter change every 30 days is the standard recommendation for most households. If you have pets or anyone in the home with allergies, change it every 20 to 30 days. For a household with no pets and no allergy concerns, you might stretch to 60 days — but I wouldn't push past that in our climate.
Buy a multipack of the correct filter size and keep them stacked near the air handler. When the old one comes out, the replacement is already in the room. Set a recurring reminder on your phone for every 30 days. The whole job takes under two minutes.
Check your lease or ask your property manager which filter size you need and what MERV rating is recommended for your system. Using a filter that's too restrictive (very high MERV rating) can actually reduce airflow just as a dirty filter does. When in doubt, a MERV 8 filter is appropriate for most residential systems in this area.
Thermostat Settings That Work With the System, Not Against It
How you set and use the thermostat has a significant impact on both system health and your electric bill.
Set it at 75–78°F when home
Florida Power & Light and other Florida utilities consistently recommend 78°F as the most efficient setting when you're home and active. Most people find 75 to 77°F a comfortable compromise. Every degree below 78°F adds roughly 6 to 8 percent to your cooling costs. Setting the thermostat to 68°F because you want it cool fast doesn't actually cool the space faster — it just keeps the system running longer once it gets there.
Raise it slightly when you're away
When you leave for work or go out for several hours, set the thermostat to 82–85°F rather than turning the system off entirely. Turning it completely off in Florida summer allows humidity to build up indoors, which is hard on furniture, promotes mold growth, and means the system has to work very hard to recover when you return. A modest setback is far better than a full shutdown.
Avoid big swings
Cranking the thermostat down to 65°F when you get home after a hot day puts enormous stress on the system and doesn't cool the space any faster than setting it to 76°F. Large, rapid temperature swings are one of the habits that shorten equipment life.
Use "Auto," not "On"
Your thermostat's fan setting has two options: "On" runs the fan continuously regardless of whether the system is actively cooling. "Auto" runs the fan only when the system is cooling. Use "Auto" in Florida. Running the fan continuously in our humid climate pulls warm, moist air across the cold evaporator coil even when the compressor isn't running, which can cause the coil to collect moisture and contribute to mold. "Auto" mode lets the coil dry between cycles.
Keep Vents Open and Unobstructed
It's tempting to close vents in rooms you're not using, thinking it will redirect cool air where you want it. In most residential HVAC systems, this actually works against you. Your system's ductwork is sized to handle a certain volume of airflow. When you close vents, you increase the pressure in the ducts, which forces air through any gaps or leaks and makes the system work harder. Closed vents can also cause the evaporator coil to freeze, which brings the system down entirely.
Keep all supply vents open. Make sure furniture, rugs, and curtains aren't blocking either supply vents (where cool air blows out) or return air vents (usually larger grilles on walls or ceilings where air gets pulled back to the handler). A blocked return is one of the fastest ways to starve the system of airflow.
Understanding the Condensate Drain Line
This is the HVAC topic most tenants have never heard of, and it's responsible for a large share of the service calls we manage. Here's the quick version: as your AC removes humidity from the air, that moisture drips off the evaporator coil into a drain pan, then exits the home through a condensate drain line — typically a white PVC pipe that runs to the outside or to a floor drain.
In Florida's warm, humid climate, algae and mold can grow inside that drain line and eventually clog it. When the line is blocked, water backs up into the drain pan, then overflows onto the air handler, the ceiling, or the floor. Many systems have a float switch that shuts the system off when the pan fills with water — which is why your AC sometimes just stops working for no obvious reason.
What tenants can do
Some property managers recommend pouring a cup of distilled white vinegar or a diluted bleach solution (one part bleach to 16 parts water) down the condensate drain line access point once a month. This inhibits algae growth and can prevent blockages before they happen. Ask your property manager if this is appropriate for your system — not all setups have an accessible clean-out port, and you shouldn't pour anything into the system without knowing where it goes.
More importantly: if you see water dripping from the air handler, puddling near the unit, or notice the system has shut off unexpectedly, report it immediately. A clogged drain line caught early is a quick, inexpensive fix. Left unaddressed, it can cause ceiling damage, drywall damage, and mold — none of which are things you want in your home or on your rental record.
Water near or under your air handler is never normal. Even a small, slow drip can cause significant damage within a few days. Submit a maintenance request the same day you notice it — don't wait to see if it stops on its own.
Keep the Outdoor Unit Clear
The outdoor condenser unit — the large metal box outside your home that makes noise when the AC is running — needs airflow to release the heat it pulls from inside your home. If it's blocked or restricted, the system can't shed heat efficiently, which forces the compressor to work harder and can lead to overheating and premature failure.
As a tenant, your job here is simple. Keep the area around the unit clear of leaves, grass clippings, dirt buildup, and any objects that might have drifted against it. Maintain at least two feet of clearance on all sides. Don't stack anything against it, don't let vines or bushes grow into the fins, and don't rinse it down with a hose unless you've confirmed with your property manager that this is appropriate. The condenser coil fins are delicate and can bend easily, which reduces airflow even more.
If you notice the outdoor unit iced over, making unusual noises (grinding, squealing, or banging), or simply not running when the thermostat calls for cooling, report it through your maintenance portal rather than trying to diagnose it yourself.
Warning Signs to Report Promptly
Knowing when something is wrong — and reporting it quickly — protects both you and the property. These are the signals that warrant a maintenance request:
Warm air from the vents
If the system is running but blowing warm or room-temperature air, the refrigerant may be low, the compressor may be struggling, or the filter may be so clogged the coil has frozen. Report it.
Unusual sounds
A properly working system should be relatively quiet. Squealing, grinding, banging, or rattling all indicate a mechanical problem that won't improve on its own.
Musty or burning smells
A musty smell often points to mold growth in the drain pan or ductwork. A burning smell suggests an electrical issue. Neither is something to live with and hope goes away.
Visible ice on the system
Ice forming on the refrigerant lines or the evaporator coil is a sign the system can't absorb heat properly — often from low refrigerant or severely restricted airflow.
Water where it shouldn't be
Drips, puddles, or staining near the air handler or the area below it. The drain line is almost certainly blocked — act the same day you notice it.
Sharply higher electric bills
A sudden spike without a change in usage habits often means the system is working much harder than it should — a dirty filter, low refrigerant, or a failing component.
What to Do When the AC Stops Working
In a Florida summer, a non-functioning AC is genuinely urgent. Here's how to handle it:
- Check the filter first. If you haven't changed it recently, a clogged filter may have caused the coil to freeze and the system to shut off. Replace the filter, turn the system to "Fan Only" for 30 to 60 minutes to let the coil thaw, then switch back to cooling. This resolves the problem surprisingly often.
- Check the thermostat. Make sure it's set to "Cool" and the temperature is actually set below the current room temperature. Check that the fan is set to "Auto," not "Off."
- Check the circuit breakers. HVAC systems often have two breakers — one for the air handler and one for the outdoor compressor. If either has tripped, reset it once. If it trips again immediately, stop and submit a maintenance request — there's an electrical issue that needs a professional.
- Check the drain pan. If the pan under the air handler has visible standing water, the drain line is clogged and the float switch has shut the system off. Submit a maintenance request noting the standing water so the response is prioritized.
- Submit your maintenance request and note the indoor temperature. If the home is above 85°F and you have children, elderly residents, or anyone with a medical condition in the home, say so clearly. This is an emergency maintenance situation under Florida law, and your property manager should respond accordingly.
Florida Statute 83.51 requires landlords to maintain rental properties in a habitable condition, which includes working HVAC during Florida's extreme heat. If your AC fails during summer, document the indoor temperature, submit a written maintenance request through your tenant portal, and keep a record. A responsive property manager will treat this as an emergency.
Keeping Your Electric Bill Under Control
The HVAC system is typically 40 to 50 percent of a Florida home's electricity consumption. A few additional habits can make a real difference on your bill without any sacrifice in comfort.
| Habit | What It Does | Estimated Savings |
|---|---|---|
| Use ceiling fans while home | Allows thermostat to be set 4°F higher with same comfort level | Up to 30% on cooling |
| Keep blinds/curtains closed during peak sun hours | Reduces heat gain through windows, especially south and west facing | 5–10% on cooling |
| Avoid running oven/dryer during hottest hours (noon–6 PM) | Reduces heat introduced into conditioned space | Varies by usage |
| Set thermostat back 7–10°F when away 8+ hours | Reduces runtime significantly without humidity buildup | Up to 10% annually |
| Change filter on schedule | Maintains proper airflow and system efficiency | Up to 15% on HVAC costs |
Turn off ceiling fans when you leave a room — fans cool people, not spaces, and a running fan in an empty room wastes electricity with no benefit.
Keep the Lines of Communication Open
The best thing a tenant can do for their HVAC system — and their tenancy overall — is report problems early and through the proper channel. At Bridge of Lions Realty, our tenants submit maintenance requests through the resident portal, which creates a timestamped record and ensures the right people are notified quickly.
Don't wait to see if a problem resolves itself. A small issue caught early is almost always a less expensive fix than the same issue discovered after it's been festering for two weeks. That's true for your comfort, your landlord's property, and your rental history — all of which benefit from prompt, honest communication.
If you're renting with Bridge of Lions and have any questions about your HVAC system or anything else in your home, don't hesitate to reach out through the portal or call our office at (904) 808-7368. We'd rather answer a quick question now than deal with a bigger problem later — and so would you.