It’s 4:00 PM in August. The thermostat is set to 72°, but the indoor temperature reads 78° and climbing. The outdoor unit is humming, the indoor fan is blowing, but the air coming out of the vents feels lukewarm. If you own a home in New Orleans, you have probably experienced this exact scenario.
As an HVAC contractor who has spent 17 years working on cooling systems across Orleans and Jefferson parishes, I see this problem daily. Homeowners often assume the system is just “working hard” against the heat. But if an air conditioner is running continuously without dropping the indoor temperature, it isn’t working hard—it’s failing. Our New Orleans AC repair service begins by testing airflow, electrical components, and refrigerant performance instead of guessing.
The Three Most Common Culprits
1. A Failing Dual Run Capacitor
The dual run capacitor is the most common point of failure in a New Orleans summer. This small, cylindrical component sits inside your outdoor condensing unit. It acts like a high-voltage battery, providing the massive jolt of electricity needed to start the compressor and keep the condenser fan motor running.
When ambient temperatures hit 95° with high humidity, the heat inside the metal condenser cabinet becomes intense. Capacitors degrade in extreme heat. When the capacitor gets weak, the condenser fan may continue to spin, but the compressor—the heart of the system that actually pumps the refrigerant—fails to start.
The symptom: The indoor fan blows air, but because the outdoor compressor isn’t running, the air isn’t cooled. If you walk outside and hear a loud buzzing or humming sound every few minutes, turn the system off immediately at the thermostat. The compressor is trying to start without the capacitor’s help, drawing massive amperage. If left running, it will burn itself out, turning a $200 repair into a $2,500 replacement.
2. A Frozen Evaporator Coil
If you check your indoor unit (usually in the attic or a closet) and see ice on the copper refrigerant lines, or if you notice water pooling around the unit, your evaporator coil has frozen.
Air conditioners do not create cold air; they absorb heat from the air inside your home. The evaporator coil gets very cold during this process. If there isn’t enough warm air blowing across the coil, the condensation that naturally forms on it will freeze into a solid block of ice. Once the coil is encased in ice, it can no longer absorb heat, and the system will just blow warm air around the house.
Coils freeze for two main reasons:
- Severe airflow restriction: A filthy air filter, collapsed return duct, or blocked supply vents.
- Low refrigerant charge: If the system is low on refrigerant, the pressure drops, which causes the temperature of the coil to drop below freezing.
What to do: Turn the thermostat from “Cool” to “Off,” but turn the Fan setting from “Auto” to “On.” This will blow uncooled air across the ice to melt it. A technician cannot accurately diagnose or repair a frozen system until it has completely thawed, which can take 12 to 24 hours.
3. A Refrigerant Leak
Air conditioning systems are closed loops. They do not “consume” or “burn” refrigerant. If your system is low on refrigerant, there is a leak. Period.
In New Orleans, the combination of high humidity and airborne contaminants often leads to formicary corrosion on the copper tubing of the indoor evaporator coil. This corrosion creates microscopic pinhole leaks. As the refrigerant slowly escapes, the system loses its ability to absorb heat.
Many unscrupulous contractors will offer to simply “top off” the system with a few pounds of refrigerant. This is a temporary band-aid, not a repair. The refrigerant will leak out again, and because modern refrigerants like R-410A are expensive, you will waste hundreds of dollars. A professional technician will use an electronic leak detector or UV dye to locate the exact source of the leak and provide options for a permanent repair or coil replacement.
When to Call a Professional
If your system is running constantly but the temperature is rising, the first thing you should do is check your air filter. If it is completely clogged, replace it, turn the system off for a few hours to let any potential ice melt, and try again.
If the filter is clean and the air coming out of the vents is still warm, do not let the system continue to run. Turn it off at the thermostat. Forcing a failing system to run continuously is the fastest way to destroy the compressor.
What You Can Check Without Making the Problem Worse
Confirm that the thermostat is set to Cool, lower than the room temperature, and showing a normal display. Check the filter and look at the outdoor unit from a safe distance. If the indoor fan runs but the outdoor unit is silent, or if the outdoor unit hums without starting, turn the system off and call. Do not open electrical panels, push a contactor by hand, or keep cycling the breaker.
When the technician arrives, expect more than a quick temperature check. The diagnostic should connect airflow, electrical readings, refrigerant temperatures, drainage, and the system’s operating sequence. If a capacitor failed, ask whether the motor amperage and condenser airflow were also checked. If the system is low on refrigerant, ask where the leak is suspected and what a permanent repair would involve. Those answers tell you whether the visit solved the cause or only restarted the symptom.
If your home is already getting hot, close blinds on the sunny side, limit oven and dryer use, keep interior doors open unless the duct design requires otherwise, and move vulnerable occupants to a cooler location. Once the system is off, use our service request form or call for active emergency conditions.