Why is my AC running but not cooling the house?
The most common causes are restricted airflow (a clogged filter or a frozen evaporator coil), low refrigerant from a leak, or an outdoor unit that isn't shedding heat because the condenser or compressor has a problem. The blower is still moving air, so the system sounds like it is working, but the air isn't being cooled.
The nuance is whether the air from the vents is warm or just weak. Weak airflow usually points to a filter, a frozen coil or a duct problem. Warm air at normal strength points to the outdoor unit or the refrigerant, and that side needs a licensed air-conditioning contractor.
Why it happens
An air conditioner doesn't make cold. It moves heat out of the house. Indoors, air passes over a cold evaporator coil and gives up its heat and moisture. Outdoors, the condenser releases that heat to the air. If any step in that loop stalls, the house stays warm while the fans keep running.
A dirty filter or blocked return can starve the coil of air until it freezes over. Ice then blocks airflow even more. Low refrigerant is a different problem. The system is sealed, so low refrigerant means a leak somewhere, and topping it off without finding the leak only delays the next failure. A failed capacitor or fan motor can leave the outdoor unit unable to reject heat, and the air inside turns lukewarm.
Florida's conditions add to this. Long cooling seasons keep systems under load for most of the year. Salt air near the coast can corrode outdoor coils. Storm-season power surges can damage compressors and control boards. Humid air also makes a struggling system feel worse, because it isn't pulling moisture out of the house.
What you can check yourself
Confirm it is set to Cool, not Fan only, and that the set temperature is below the room temperature. Fresh batteries fix some unresponsive units.
Pull the filter and look at it. If it is gray and matted, replace it and give the system time to recover. A clogged filter is the most common cause of poor cooling.
Look at the refrigerant line at the outdoor unit and at the indoor unit if you can see it. Ice means airflow or refrigerant trouble. Turn the system off and let it thaw before running it again, since running it frozen can strain the compressor.
Check that the fan is spinning and that leaves, mulch or fencing aren't crowding the unit. Don't open the cabinet or touch the electrical parts.
Check the breaker for the outdoor unit and the air handler. Make sure supply vents are open and not blocked by furniture.
When to call a pro
If a fresh filter and the checks above don't help, the cause is likely a refrigerant leak, an electrical part or the compressor. Call a pro if the coil keeps freezing, the outdoor unit hums but the fan won't spin, a breaker keeps tripping, or water is leaking around the air handler. Refrigerant work and electrical repairs on the outdoor unit are not DIY jobs.
Florida requires air-conditioning work to be done by a certified or registered air-conditioning contractor licensed through the state's Construction Industry Licensing Board. If the system needs replacing, the contractor pulls the mechanical permit with your city or county building department. Verify local requirements with that department. Call USA Home Repairs and we match you with a licensed air-conditioning contractor near you. The estimate is free, and you approve the price before any work starts.
What a pro will do
- Diagnose the cause
The pro checks airflow, the coils, the electrical components and the refrigerant circuit to find out why the air isn't cooling, rather than guessing.
- Find and repair refrigerant leaks
If refrigerant is low, the pro locates the leak and repairs it before recharging the system.
- Fix failed parts
Capacitors, fan motors, contactors, control boards and thermostats are common repairs. Surge damage and coastal corrosion are frequent culprits in Florida.
- Clear the condensate drain
A clogged drain line can shut the system down or leak water into a ceiling or closet. The pro clears it and checks the pan.
- Advise on replacement
If the system is worn out, the pro explains the options, including change-outs to current SEER2 efficiency standards, and handles the permit.
Related questions
Can I just add refrigerant myself?
No. Refrigerant handling is regulated and the system is sealed, so low refrigerant means there is a leak. A contractor needs to find and fix the leak, or the problem returns.
Why is there ice on my AC?
Ice usually forms from restricted airflow, such as a dirty filter or blocked return, or from low refrigerant. Turn the system off so it can thaw. If the ice comes back after a new filter, have a contractor look at it.
Could a power surge cause my AC to stop cooling?
Yes. Surges, common during hurricane season and thunderstorms, can damage compressors, capacitors and control boards. The system may still run but fail to cool.
How do I get a free estimate?
Call USA Home Repairs at (888) 996-7488 and we match you with a licensed air-conditioning contractor near you. The estimate is free, and you approve the price before anything starts.
Want a pro to look at it?
Leave your number and we call you right back to set a time. Every visit is a free estimate, with no obligation, and we'll match you with a licensed air-conditioning contractor near you.
Rather talk to someone? Call (888) 996-7488.