Updated June 2026 · Written and reviewed by Mike Mavromatis, Owner of Air It Up Air Conditioning & Heating, serving Greater New Orleans since 2000.
When an air conditioner runs but the house won't cool, the most common causes are a clogged air filter choking airflow, low refrigerant from a leak, a frozen evaporator coil, or a dirty outdoor coil that can't shed heat — sometimes simply a tripped breaker. A few of these you can safely check yourself; the rest need a technician. Here's how to tell them apart before the next Gulf Coast heat wave.
What actually stops an AC from cooling?
Cooling depends on a chain: enough airflow across the indoor coil, the correct refrigerant charge, and a clean outdoor coil to dump heat outside. Break any single link and the system runs — the fan blows, the compressor hums — but the temperature never drops. Diagnosing a no-cool call is really about finding which link in that chain is broken.
What you can safely check first
- Replace a dirty air filter and confirm the thermostat is set to cool with the temperature below the room reading.
- Check the breaker — a tripped circuit (common after a summer power surge) stops the outdoor unit while the indoor fan keeps running.
- Clear leaves, grass clippings, and debris off the outdoor condenser so it can breathe.
- Make sure all supply registers are open and return vents aren't blocked by furniture.
If a fresh filter, a reset breaker, and a clear outdoor unit restore cooling, you've solved it. If not, the problem is deeper.
Failure modes that need a professional
Low refrigerant means a leak — adding more without finding and fixing the leak just wastes money and re-pollutes the system. A failed compressor or start capacitor, or a coil that has frozen into a block of ice, also require a technician. A frequently overlooked culprit in our climate is a dirty outdoor coil caked with pollen and grass — it can't reject heat, so the house never cools no matter how long the unit runs. Continuing to run a struggling system through New Orleans summer heat risks turning a small repair into a compressor replacement.
Proof: what we see in the field
Most no-cool calls our technicians run across Gretna, Metairie, Kenner, and the West Bank come down to airflow or charge, and many are quick fixes caught early. The homeowners who fare worst are the ones who keep a warm-blowing system running for days in July — that's how a $200 capacitor turns into a four-figure compressor job. Catching it early is almost always cheaper.
Repair or replace — and your next step
If your AC is older and the repair is significant, it may be worth weighing a replacement instead of another fix — our honest repair-or-replace framework walks through age, repair cost, and efficiency. A coil that keeps freezing is a related symptom worth understanding too — see why an AC freezes up. When the basics don't restore cooling, book an AC repair and we'll diagnose it honestly with upfront pricing — or reach us for emergency service when it fails on the hottest day. Learn more about our air conditioning repair and service across Greater New Orleans, or call (504) 915-9747.