Air conditioners consume a lot of energy as they convert warm air into cooled air. The more energy they use, the more expensive your energy bills can become. This is why it’s so important to invest in regular AC maintenance. Regular AC maintenance can help you avoid AC problems, including AC that won’t shut off. If you’re asking, “why won’t my AC shut off,” here’s a look at 10 possible answers.

1. The Compressor Contactor Gets Stuck Open

The AC uses a contactor to control electricity coming from the compressor. A closed contactor means there is electricity flowing from the compressor to the motor. When it’s open, the flow of electricity stops.

Compressor contactors can become stuck closed or open when dirt or debris gets in the system and along the contactor. This can stop the motors from working, and the electricity will flow constantly. The AC will be unable to shut off, and the compressor will run continuously despite thermostat settings. This can lead to soaring bills, uncomfortable indoor temperatures, and a damaged system. Repairing or replacing a stuck contactor will prevent this from happening.

2. The Evaporator Coils Freeze

When evaporator coils freeze, the AC is no longer able to cool effectively and may only blow warm or hot air. This commonly occurs when condensation forms during the cooling process and freezes on the surface of the AC’s evaporator coils. The coating of ice on the coils keeps the refrigerant from making the air cold.

Signs of frozen evaporator coils include ice on the outdoor refrigerant line, condensation around the air handler, and overflowing or clogged drains. Ice isn’t the only factor in frozen coils. Dirt and dust can also build up and strain your system. Cleaning them periodically can ensure proper heat absorption and reduce the risk of freezing.

Finally, frozen coils can also result from clogged drain pans and dirty drain lines. A technician can clean frozen evaporator coils in a single session.

3. The Thermostat Goes Dead

The thermostat acts as the brain of your home’s HVAC system. It monitors the current indoor temperature and uses the information to turn the system on and off to maintain your desired temperature using warm or cool air. It can turn the AC on or off to maintain a specific temperature, but if the thermostat loses power or dies, the AC might not turn on or off. Changing the batteries in your thermostat once a year can prevent this from occurring.

4. The Blower Fan Not Set on AUTO

Your AC might not shut off because of the setting. Most air conditioners have two fan settings: ON and AUTO. When set to the ON position, the AC fan will stay on until you manually change the setting. When set to the AUTO position, the AC fan will cycle on and off as necessary to maintain its temperature setting. Switching your AC to the AUTO setting should fix the issue and ensure the AC only comes on as needed.

5. The Condenser Is Dirty

The condition of your air conditioner’s condenser, which is probably outside and close to your house, affects how your cooling system works. A clean condenser allows for the most effective cooling, while a dirty one restricts airflow and makes it hard to make cool air. As a result, the system will continuously run in an attempt to maintain temperature settings. Getting the condenser cleaned during annual maintenance will help you avoid this type of problem.

6. The AC Short Circuits

An AC that short circuits will often get stuck in the ON position. The short circuit will stop all communication from the AC to the thermostat, meaning the thermostat can’t instruct the AC to shut off. The only way to shut the system off is by flipping the breaker.

Ideally, the system will kick back on with no issues. Fixing short circuits requires skilled expertise and should get performed by those with electrical training.

7. The Air Filter Gets Clogged

The AC filter plays a large role in how often the AC kicks on and off. When the filter is clean, the airflow is at its best, so the AC can cool the house quickly without having to turn it on and off all the time.

Air filters work to collect pollen, dust, dirt, and other airborne particles as they pass through the system. As they capture debris, they become dirtier. When the filter becomes dirty and clogged, the air conditioner has to work harder to keep up. This not only increases your energy bills but also can increase the risk of the unit overheating. Your AC unit might also run often or all the time while failing to cool your air adequately, and your indoor air may feel stagnant.

Replacing the air filter regularly can ensure your indoor air stays clean and fresh and that your air conditioner is running optimally. You also need to double-check that you’re using the correct size filter. The wrong-sized filter can lead to a malfunctioning AC unit, too.

8. The AC Is the Wrong Size

Air conditioners come in a variety of sizes. If you’re remodeling your home or adding an addition, you must first check to see whether the AC can handle the extra load. If the air conditioner is too small, it won’t have the power to attain the cooling temperatures you want.

An undersized AC system will use a tremendous amount of energy to run around the clock and will still be inefficient as it attempts to cool your space. Your cooling expenses will skyrocket. Until you replace your system with one that is better sized for your home, your AC will run for hours trying to make your space comfortable.

9. The Wires Are Loose

Loose wiring is another potential cause of an AC that won’t shut off. Over time, wiring becomes dirty. Even layers of protection, such as insulation, can deteriorate to the point where the wires become exposed.

When exposed wires maintain a constant connection, the condenser will continue to operate and the AC won’t shut off. Common causes of exposure include dirty wiring, external damage through the walls, and damage from pests. Regardless of the cause, a professional should handle all electrical issues.

10. The Refrigerant Leaks

Air conditioners come with a certain amount of refrigerant. Refrigerant draws heat and humidity out of the home to achieve the cool temperature you want. When the refrigerant lines are compromised, the coils are broken, or the system is otherwise malfunctioning, the AC is simply unable to cool effectively. It will run nonstop in an attempt to cool your home.

You may need to have the refrigerant levels refilled, the damaged coils repaired, or defective components replaced to correct the issue.

Get Your AC to Shut Off Today!

Technicians must inspect several components of the HVAC system to determine the cause of an AC that won’t turn off. Many of these parts can be hard to get to and require the presence of a professional. Whether you need a clean air filter installed or a faulty thermostat rewired, At Your Service Heating & Cooling LLC is here to help. Contact us today to learn all about our premier HVAC, plumbing, and electrical services. Instead of worrying about an AC that won’t shut off, contact us today and let us fix the problem. We help people just like you improve their indoor comfort while also following energy-saving practices.

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