A Florida house starts heating up. The thermostat says “cool,” the air handler is humming, and the air at the registers feels warm. The next thought is usually “how soon can a technician get here?” Before that call goes out, a homeowner can usually run through six quick checks in about fifteen minutes. About half of the warm-house service calls on the Treasure Coast turn out to be one of these six things, and a few of them can be reset without any tools at all.
This is not a checklist designed to talk anyone out of real A/C repair. A failing compressor still fails. A leaky refrigerant circuit still leaks. But a tripped breaker, a filter no one has touched since hurricane season, or a float switch that did exactly what it was designed to do can all look like a broken air conditioner from the kitchen. Knowing which is which saves a service-call fee on the easy fixes and helps a certified comfort technician arrive prepared on the real ones. Below is the order our team uses on the phone when a homeowner in Stuart, Palm City, Jensen Beach, Port St. Lucie, Fort Pierce, or Jupiter calls in about a warm house.
Is the Thermostat Set Up the Way You Think It Is?
Almost a third of “my A/C is broken” calls trace back to a thermostat that is doing exactly what someone told it to do. The frame is not whether the thermostat is alive, but whether it is set, scheduled, and powered the way the homeowner expects.
The Mode, the Setpoint, and Dead Batteries
Confirm the mode reads “cool” and not “fan only,” “auto,” or in shoulder-season homes “heat” with a low setpoint. The setpoint should be at least three degrees below the current room temperature, otherwise the thermostat is not actually calling for cooling. After a power blip from an afternoon thunderstorm, some thermostats reset to a default schedule that holds the house at 78 or 80 even when the family is home. Pull up the current setpoint, the mode, and the schedule on the screen before anything else.
Most wired thermostats also run on a pair of AA batteries as a backup for the screen and the wireless radio. When those drain, the display can stay lit for a while but the relay that calls for cooling stops working. Swap the batteries first if the screen looks dim, the buttons are slow to respond, or there is any low-battery icon in the corner of the display.
A Tripped Breaker on the Thermostat Side
This one catches a lot of people. In many Treasure Coast homes from the 1990s and 2000s, the low-voltage transformer that powers the thermostat runs off a 120V circuit shared with a bathroom GFCI, a vent fan, or a hallway outlet. If a curling iron tripped a GFCI down the hall last night, the thermostat may simply have no power going into it. Walk the breaker panel and reset any half-tripped breakers. Then walk the GFCI outlets, especially in bathrooms and the laundry room, and press the reset button on any that show a popped center.
When Was the Air Filter Last Changed?
The filter is the single most overlooked piece of an A/C system, and it is also one of the only parts a homeowner is supposed to service. A loaded filter starves the indoor coil for airflow, drops cooling capacity, and eventually freezes the coil into a block of ice. From the kitchen it looks like “the unit is running but nothing cold comes out.”
The Florida Change-Out Rhythm
Filter packaging usually says “every 90 days.” Treasure Coast humidity, salt-and-pollen-heavy lanai season, and long compressor runtimes say something different. A standard one-inch pleated filter in a four-person household with one pet usually needs a swap every 30 to 45 days from April through October. Two pets, open-door tropical living, or recent drywall work can pull that down closer to every three weeks. A filter that has not been pulled since the snowbird homeowners flew north in March is a common discovery on May service calls.
Where the Filter Actually Lives
Single-return homes have one filter behind a louvered grille in a hallway, ceiling, or laundry-room return. Multi-return homes can have a filter at every return grille, or a single, larger filter slot at the air handler itself in a garage closet or attic platform. Look for the air handler first, identify the cabinet with the cold suction line going into it, and check whether there is a filter rack at the bottom of the cabinet. A central return filter at the air handler is the one that controls airflow across the indoor coil. That is the one that matters most for the no-cool problem in front of you.
What “Too Dirty to Ignore” Actually Looks Like
A new filter is white or off-white. A filter that has done its job for 30 days in Florida summer turns gray. A filter that has not been changed in six months turns dark brown, and may collapse inward in the middle when air pulls through it. That collapse is the start of a frozen coil and a major repair call. Pull the filter, hold it up to a hallway lamp or a ceiling light, and replace it if no light comes through. Catching a filter at this stage during an annual A/C maintenance visit is the cheapest insurance policy against a no-cool call the following week.
Did the Outdoor Unit Lose Power on Its Own Circuit?
Almost every central A/C in Florida runs on two separate breakers. The indoor air handler has a smaller breaker, usually 15A to 30A, and the outdoor condenser has a larger one, usually 30A to 60A on a double-pole. A tripped outdoor breaker is the single most common reason a thermostat says “cooling” and no cold air comes out: the indoor fan still runs from the indoor circuit, but the compressor and outdoor fan are dead from a popped outdoor breaker.
Two Breakers, One Panel
Open the main breaker panel and look for two A/C-related breakers, usually labeled “A/C,” “AHU” (air handler unit), or “Condenser.” If either is sitting at a halfway position between on and off, that is a trip. Flip it fully to off, wait a full ten seconds, then flip it back to on. Do not slam it. The breaker should hold. If it trips again within ten or fifteen minutes, stop resetting it and call: a breaker that trips twice in a row is signaling a real electrical fault and repeated resets risk an arc fire.
The Disconnect Box on the Side of the House
There is also a metal box mounted to the wall right next to the outdoor unit, with a pull-out handle inside the cover. That handle is the local service disconnect. Storm crews, pressure-washers, pool-service techs, and lawn crews sometimes pull it for safety and forget to slide it back in. If both breakers in the panel look fine, walk to the outdoor unit, lift the disconnect cover, and confirm the pull-out is fully seated. Some disconnects also have a small fuse holder inside the box that can blow on a surge.
When the Power Is Good But Nothing Starts
If both breakers are on and the disconnect is in but the outdoor unit still will not start, the issue is past where most homeowner checks stop. The contactor inside the outdoor unit can chatter, stick, or burn its contact points. The dual-run capacitor can swell or fail outright. Listen at the outdoor unit while the thermostat is calling for cool. Silence at the condenser means the call is not making it through to the compressor, and a compressor that will not start even with power needs a meter and a parts-stocked truck, not another breaker flip.
Is There Ice or Water Where There Should Not Be?
Two final visual checks are worth doing before picking up the phone. They are the two checks most likely to change how a service call gets dispatched.
Ice on the Suction Line at the Outdoor Unit
Walk outside and look at the larger of the two copper lines going into the outdoor unit, the one wrapped in foam insulation. If it has a sleeve of frost or visible ice on it, the indoor coil is frozen. Running the system any longer pushes liquid refrigerant back into the compressor and risks damaging it. Switch the thermostat to “fan only” for four hours to let the ice melt, change the filter while waiting, and then test “cool” again. A unit that frosts up a second time has ice forming on the indoor coil from a low refrigerant charge as the cause, not the dirty filter, and that is past the homeowner stage.
Water Where the Air Handler Sits
Check the closet, garage, or attic platform where the indoor unit lives. If the floor around the unit is wet, if the secondary safety pan under the air handler has water in it, or if the ceiling drywall below an attic system shows a stain, a drain backup has already happened. Most modern systems have a tripped float switch in the safety pan that shuts the system off before the water reaches drywall. From the kitchen, that looks like “thermostat is calling, nothing happens.” Clearing the drain line is a fifteen-minute tech job, but identifying the wet pan before the truck rolls saves diagnostic time on the call.
What’s the Right Next Step for a Treasure Coast Homeowner?
If the six checks above all pass and the house is still warm, the diagnosis is past the homeowner stage and into a real service visit. Knowing that ahead of time is the value of the checklist. The phone call to dispatch can now start with “I have checked the thermostat mode and setpoint, the filter, both breakers, the outdoor disconnect, no ice on the line set, no water under the air handler, and the system still will not cool.” A certified technician walks in already past the easy stuff, with a multimeter and a capacitor inventory in hand.
For homes across Stuart, Palm City, Jensen Beach, Hobe Sound, Port Salerno, Port St. Lucie, Fort Pierce, and Jupiter, the Honest Air dispatch desk can usually schedule an A/C repair visit inside a single business day during peak season. Showing up with a half-completed checklist is the fastest way from a warm kitchen to a cold one.
Frequently Asked Questions
How much of an A/C problem can a homeowner really diagnose at home?
About half of warm-house service calls in any Florida summer turn out to be one of five things a homeowner can identify or reset: a thermostat in the wrong mode, a tripped breaker, a dirty filter, a pulled disconnect, or a drain-pan float switch that did its job. None of those require a technician. The other half, including bad capacitors, failed contactors, low refrigerant charges, compressor faults, and fan motor failures, all need test gear and parts on the truck. The checklist sorts which call you are about to make and helps the technician arrive prepared.
Should I turn the A/C off completely while I run through the checks?
Yes. Switch the thermostat to “off” before opening the air handler closet, pulling a filter, or resetting a breaker. Leaving the system calling for cool while panels are off can pull warm humid air through an open cabinet and trigger a coil freeze on top of whatever was already wrong. Set the thermostat back to “cool” only after the panel is closed and the filter is back in place.
Will resetting a tripped breaker damage my A/C?
A single reset is part of normal operation. Breakers trip on overcurrent for a reason, but a one-time bump from a storm, a pool pump kicking on, or a brown-out is common and harmless to reset. If the same breaker trips again within ten or fifteen minutes, stop resetting it. A breaker that trips twice in a row is signaling a real electrical problem, often a shorted capacitor, a stuck compressor, or chafed conductors, and repeated resets risk arcing inside the disconnect or panel. That second trip is the moment to call.
How do I know when a filter is too dirty instead of just used?
Hold the filter up to a hallway lamp or a ceiling light. A clean filter shows a distinct pleat pattern and lets light through clearly. A filter at the end of its useful life is opaque. A pleated filter that has darkened to the color of strong coffee and that pulls inward in the middle when the system runs is past replacement. A filter with visible black or green spots has mildew and goes straight in the trash. None of these stages are repairable. The fix is a new filter, not a vacuum-and-reinstall.
Why does my A/C have two breakers in the panel?
The indoor air handler and the outdoor condenser have very different startup loads. The indoor blower draws a steady, modest current that fits on a 15A or 20A breaker. The outdoor compressor pulls a brief, large surge at startup that needs its own circuit and a breaker sized for that surge, usually 30A to 60A. Keeping them on separate breakers also means a technician can isolate one side of the system for testing without shutting the other side down, and lets a homeowner reset one without touching the other.
My A/C is fifteen years old. Should I keep paying for repairs?
That question is bigger than this checklist. The honest version is that compressor age, refrigerant type (especially R-22 versus R-410A versus the newer R-454B), salt-air corrosion on coils, and current energy bills all weigh into the keep-or-replace call. A pre-call checklist saves a service fee on the easy fixes today. A real conversation about whether the system is at the end of its design life is a separate visit with a different scope, usually scheduled after a real diagnostic on the current issue, not from a phone quote.
