Across Florida · Vetted local pros
Why is my AC running constantly but not cooling the house?
A straight answer first, then what you can safely check yourself and when to get a pro. Free estimates from a vetted MB pro near you.
An AC that runs all day without cooling is usually short on airflow or heat transfer. The common causes are a clogged filter, a frozen or dirty evaporator coil, a dirty outdoor coil, low refrigerant from a leak, or a failing part such as a capacitor or fan motor.
Some causes are easy to rule out yourself: thermostat settings, a dirty filter, blocked vents, and debris around the outdoor unit. Refrigerant, electrical and internal repairs belong to a licensed air-conditioning contractor.
Why it happens
Your AC cools by pulling heat out of the indoor air and releasing it outside. If anything interrupts that, the system keeps running because the thermostat never reaches its setting. Restricted airflow, ice on the indoor coil, a dirty outdoor coil, or a refrigerant shortage can each stop the heat moving.
Florida's heat and humidity make this worse. The system runs most of the year, so filters clog and coils collect dirt and moisture. Near the coast, salt air can corrode outdoor coils. After a storm, a power surge or outage can leave a compressor or control board weakened, so the unit runs but delivers little cooling.
Size and age matter too. An older or undersized system, or leaky ductwork, may run constantly on the hottest afternoons and still fall behind. A pro can tell the difference between a repairable fault and a system that is simply worn out.
What you can check yourself
Thermostat settings
Confirm it is set to Cool, the fan is on Auto, and the temperature is set below the room temperature. Dead batteries or a blank screen can also cause odd behavior.
The air filter
Switch the system off at the thermostat, then look at the filter. If it is gray and clogged, replace it with the right size. A clogged filter is one of the most common causes of weak cooling.
Vents and returns
Walk through the house and feel the airflow at each supply vent. Make sure furniture, rugs or closed doors are not blocking vents or return grilles.
Look at the outdoor unit
From a distance, check that the fan is spinning and that leaves, grass or bags are not packed against the unit. Keep plants trimmed back from it. Do not open panels or spray into it.
Look for ice or water
Check the indoor unit and the refrigerant line for frost, and the floor and ceiling nearby for water. Frost or a wet area means turn the system off and call a pro. Running it can make the damage worse.
When to call a pro
Stop and get a pro if the filter is clean and airflow is fine but the air is still warm. The same goes for ice on the coil or line, a humming outdoor unit with a stopped fan, a burning smell, a breaker that keeps tripping, or water around the air handler. Do not add refrigerant or open electrical panels yourself.
Florida requires AC repair and replacement to be done by a licensed air-conditioning contractor, or a mechanical contractor whose license covers it. A building or roofing license does not cover AC work. You can verify any license number on the Florida DBPR website. A full system change-out typically needs a mechanical permit, which the contractor pulls. We match you with a vetted pro near you and book the visit. MB matches homeowners with a pro for AC & heating in Miami-Dade, Broward and Palm Beach counties only.
Your MB pro handles the permit when the job needs one. You can look up a contractor's license at Florida DBPR.
What a pro will do
- Diagnose the causeYour MB pro checks airflow, the coils, the fan motors, electrical components and the thermostat to find where cooling is being lost.
- Check for refrigerant leaksIf the charge is low, the pro finds the leak and repairs it rather than only topping off the refrigerant. Ask them to explain what they found and where.
- Clear drains and clean coilsA clogged condensate drain, a frozen evaporator or a dirty outdoor coil can be cleared and the system tuned up.
- Repair or replace partsFailed capacitors, motors, control boards or thermostats can be replaced. If the system is past repair, the pro explains replacement options and the permit involved.
- Give a free estimateCost depends on the fault found, the part, access to the unit, system age, and whether a permit is needed. Ask for the options in writing before work starts.
How it works
Step 1
Tell us what you need
Call or send the short form with your city and the job. Estimates are free.
Step 2
We match you with a vetted pro near you
We pick a vetted pro from our network who works in your part of Florida and book the visit.
Step 3
Your pro gives a free estimate and does the work
Your MB pro looks at the job and gives you a free estimate. You decide whether to go ahead — and we stay your point of contact.
Related questions
- Is it bad to keep running my AC if it isn't cooling?
- If there is ice on the coil or line, or water leaking, turn it off at the thermostat. Running a frozen system can strain the compressor and cause leaks. If it simply cools weakly, a pro should look at it soon.
- Can a dirty filter really stop my AC from cooling?
- Yes. A clogged filter restricts airflow, which can freeze the evaporator coil and leave the house warm. It is the first thing to check, and a quick one.
- Does low refrigerant just need a recharge?
- Refrigerant does not get used up, so low levels usually mean a leak. A licensed air-conditioning contractor should find and repair it, because topping off alone tends to bring the problem back.
- Could the AC just be too small for my house?
- It can be. An undersized system, or one with leaky ducts or poor insulation, may run constantly on hot days. A pro can check sizing and ductwork as part of the estimate.
- How do I get a pro to look at it?
- Call (954) 707-6550 or use the form on the page for a free estimate. We take the request, match you with a vetted pro near you and book the visit.
Keep reading
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- 1Tell us what you need.
- 2We match you with a vetted pro near you.
- 3Your pro gives a free estimate and does the work.
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