When your AC stops working in Miami, don't panic — and don't immediately call a technician. A surprising number of AC "breakdowns" in South Florida homes are caused by simple issues you can resolve in minutes without paying a service call fee. Work through this checklist first. If none of these fix the problem, then it's time to call in the pros.
1. Check Your Thermostat Settings. This sounds obvious, but it's the first thing any technician will check. Make sure the thermostat is set to "Cool" (not "Heat" or "Fan Only"), that the temperature setpoint is lower than the current room temperature, and that it's set to "Auto" not "On" ("On" runs the fan continuously even when the system isn't cooling). If your thermostat is battery-powered, try replacing the batteries. In Wynwood loft apartments and older Coral Gables homes especially, we see thermostats accidentally switched to "Heat" after housekeeping or guests adjust the settings.
2. Inspect Your Air Filter. A severely clogged air filter is the number one cause of AC problems in South Florida. Miami's combination of high humidity, outdoor dust, pollen, and pet hair (if applicable) clogs filters faster than in dry climates. A blocked filter restricts airflow so severely that the system can't cool properly, can cause the evaporator coil to freeze, and can trigger the system to shut down entirely on safety. Pull out your filter — if you can't see light through it, replace it immediately. Filters should be changed every 30–60 days in South Florida, not every 90 days as the packaging often suggests.
3. Check Your Circuit Breaker. Go to your electrical panel and look for the breaker labeled "AC," "Air Handler," or "Condenser." Most homes have two separate breakers for the AC system — one for the air handler inside and one for the outdoor unit. A tripped breaker will be in the middle position rather than fully "On" or fully "Off." Reset it by switching it fully to "Off" and then back to "On." If the breaker trips again immediately, do not keep resetting it — that indicates a serious electrical problem that needs professional attention. Miami's frequent summer thunderstorms are a common cause of tripped AC breakers.
4. Clear Your Condensate Drain Line. This is a uniquely Miami problem. Your AC system removes moisture from the air as it cools — in South Florida, that can be 5–20 gallons of water per day during humid summer months. That water drains out through a PVC pipe called the condensate drain line. In Miami's warm, wet climate, algae and mold grow inside that pipe and can create a complete blockage within months. When the drain clogs, water backs up into the drain pan, triggers a float switch that shuts down the system, or overflows into your ceiling or walls. Locate the condensate drain line (usually a white PVC pipe exiting the air handler toward a drain or outside), and pour a cup of distilled white vinegar or a condensate drain treatment tablet into the access port monthly to prevent clogs. If you suspect it's already blocked, try using a wet/dry vacuum on the outdoor end of the pipe.
5. Inspect the Outdoor Unit. Head outside and look at your condenser unit. Is the fan spinning when the system is running? Is there visible ice forming on the refrigerant lines or coils? Is the unit surrounded by overgrown vegetation? In Miami's lush landscaping environment — particularly in neighborhoods like Pinecrest, South Miami, and the Redlands — plants grow fast and can block airflow to the condenser within a season. Clear any debris and ensure at least 2 feet of clearance on all sides. If you see ice on the coils or refrigerant lines, turn the system off and let it thaw (run the fan only for 1–2 hours) before restarting — continuing to run a frozen system can destroy the compressor.
6. Check All Your Vents. Walk through your home and make sure every supply and return vent is open and unobstructed. Furniture pushed against vents, closed vent dampers, and debris in return air vents are all common culprits. In particular, check that no one has closed multiple vents to "redirect" airflow — modern AC systems are designed to move a specific volume of air, and closing too many vents creates back-pressure that stresses the system and can cause freezing or compressor damage.
7. Check Your FPL Account for Outages. FPL (Florida Power & Light) serves most of Miami-Dade and Broward County. Before assuming your AC is broken, quickly check the FPL outage map at fpl.com or the FPL app to see if there's a power outage affecting your area. Partial outages — where you have some power but not full voltage — are particularly tricky because lights may work while 240-volt appliances like your AC don't. If neighbors are also without power, the problem is FPL's, not your system.
If you've checked all seven items and the AC is still not working, it's time to call a professional. Some problems — refrigerant leaks, electrical faults, failed compressors — are genuinely dangerous to attempt yourself and require licensed technicians with proper equipment. Attempting a DIY refrigerant recharge, for example, is illegal without EPA certification and can cause serious injury.
MGM A/C Appliances provides 24/7 emergency AC service across Miami-Dade County with no after-hours surcharge. If your system isn't cooling and you can't find the cause, call us at (786) 352-0084. Our bilingual technicians will diagnose the problem fast and give you an upfront price before any work begins.