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Why is My AC Not Cooling?

Sweating through a sleepless night or slogging through the heat of a sweltering afternoon? It’s frustrating when your air conditioner isn’t cooling. And it usually happens on the hottest days of the year. Regular air conditioner maintenance can help prevent this issue.

Air conditioning systems are more than just the outdoor condenser unit. They include an indoor air handler (furnace or fan coil), evaporator coil, air filter, thermostat, and refrigerant lines connecting the indoor and outdoor units. Several factors can cause your AC to stop cooling, but it doesn't always mean expensive repairs or replacement. Here are some common causes and solutions.

Reasons Why Your AC Isn't Cooling

Thermostat Issues

First, check your thermostat settings. Ensure it’s set to cool and the temperature setting is correct. If it’s off or set to heat, switch it back to cooling. After the system kicks on, wait a few minutes, then check if cold air is blowing. If not, move on to the next step.

Dirty Air Filter

A dirty air filter can block airflow, reducing your AC’s cooling capacity. It can even cause the system to shut down completely. Locate the air filter, turn off the system, remove the filter, and inspect it. If it's dirty, replace it. If your central air conditioner still doesn't cool your home after replacing the filter, you’ll have to dig a little deeper to find the problem.

Blocked Condenser Unit

Your outdoor condenser unit might be blocked by dirt, grass, or debris. This prevents it from pulling heat out of your home. The exterior of the condenser unit features a large outdoor coil with thin metal fins. When these fins get clogged, the unit's efficiency drops. Clear away debris, carefully vacuum the coil with a brush attachment, or rinse it gently with a hose. If it still isn’t cooling, it’s probably time to call a professional.

Frozen Evaporator Coil

The indoor component of your central air conditioning system includes an evaporator coil. Signs of a frozen evaporator coil include frost on the copper refrigerant tubing, inadequate cooling, higher utility bills, and excessive condensate drainage. Accessing the evaporator coil is difficult, so resolving issues associated with it is best handled by an HVAC professional.

Refrigerant Leak

Refrigerant is crucial for the cooling process. A leak can cause your AC to run longer without effectively cooling your home. It can also lead to a damaged compressor and complete system shutdown. Checking and resolving refrigerant levels is a job for your local HVAC technician.

Undersized Air Conditioner

Air conditioners are sized according to the amount of cooling they can provide, measured in BTUs per hour (BTUh). If your AC is undersized, it may run for long periods and struggle to keep you cool, especially as temperatures rise outside.

Determining the correct size involves factors like square footage, insulation quality, and local climate. If your system is undersized, consider adding a ductless unit or replacing the system with one that is correctly sized. Consult a qualified HVAC professional to accurately assess your home’s cooling needs.

Get Help from Cape Air Conditioning

If you’ve tried these solutions and your AC still isn’t cooling, it’s time to call Cape Air Conditioning. Running your AC without proper cooling can lead to major issues. Contact us for professional assistance and ensure your home stays comfortable.

For more detailed troubleshooting, check out our troubleshooting guide.


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