Even if you have a top-tier air conditioning unit, you’ll need to address issues like an AC that runs nonstop. This common air conditioner problem affects your family’s comfort and raises your monthly energy bills. An AC that won’t turn off will have similar issues to an air conditioner that turns off at night. Faulty components such as the AC sensor or compressor contactor can interfere with the cooling function of the unit.


  • A constantly running air conditioner is a sign of underlying issues with your AC hardware and maintenance.
  • Dirty air filters are a common cause of an always-on AC unit because the restricted airflow will freeze the coils.
  • Your problem might be a faulty contactor or low refrigerant levels. You should contact a professional technician if coolant or electronic components are causing the power problem.

Extended air conditioner run times will consume unnecessary electrical power, a deeper issue for those running their AC from a generator. Often, you’ll experience poor air movement because the AC unit cannot meet the cooling demands of your household.

Insider Tip

Installing a clean filter is a simple maintenance task critical to maintaining your AC system’s health.

Undersized Air Conditioner

Air conditioner sizes matter for maintaining a comfortable temperature in your home. For example, the efficiency level of a 4-ton AC vs a 5-ton model is different enough to impact your air conditioner cycle. If your AC unit doesn’t have enough BTUs to suit the square footage of your home, it has to work continuously to reach the correct temperature.

Restricted Airflow from Vents

Ensure that your air vents are open and unobstructed; otherwise, your central air conditioner cannot adequately distribute the cool air. In addition, if the vents or ducts are too dirty, cool air cannot efficiently flow from the ducts. In this case, you’ll want to use vinegar to clean the AC drain line. That’ll help airflow and performance.


Only a licensed service professional can legally handle AC refrigerants, so call one if you need a coolant recharge.

Faulty Contactor

The contactor is in the outdoor unit, and it distributes electric power to the electrical components of your AC. In addition to activating the external compressor and condenser fan, the contactor also turns the AC on and off. The contactor features a physical switch, which can get stuck in the “on” position. Without professional services, the electrical circuit will not switch off, leading to a constantly-running AC. If you own a unit with smart features like the best smart air conditioner, smartphone apps can make diagnosing AC problems easier by telling you directly what’s wrong.

Dirty Air Filter

The buildup on a dirty filter can block the airflow in the entire unit, causing your AC to work overtime to reach your desired temperature. Since the cooled air cannot escape the unit, your evaporator and condenser coils can freeze. If you have the correct filter size, replacing the AC filter is a simple maintenance task.

STAT: A US EIA (Energy Information Agency) survey shows that 93% of Americans in the South Census Region use an air conditioning system. (source)

Refrigerant Leak

An AC unit with low refrigerant levels cannot efficiently cool your home. Without a refrigerant charge from an HVAC professional, your air conditioner has to work harder and longer to cool your home. In addition, you’ll eventually have frozen evaporator coils since there isn’t enough coolant to absorb heat from your home. And if those coils are dirty, be sure to know how to clean AC coils as well to prevent issues.

Why Does My Air Conditioner Run All the Time FAQs

How do air conditioners work?

The liquid refrigerant inside your evaporator coil converts to gas, and the refrigerant absorbs the heat from the indoor air. This process cools the air, and the blower fan distributes the chilled air into your air vents and home.

Is it OK for an air conditioner to run all day?

You can keep your AC powered on all day, but the compressor shouldn’t be working the entire time. A normal cooling cycle should occur one to three times per hour for about 15 to 20 minutes each. Once your thermostat detects your desired indoor temperature, the compressor should turn off.

When should I replace my air conditioner?

EnergyStar recommends replacing your air conditioner unit every 10-15 years to keep your system energy efficient and effective. That said, you may get a longer lifespan with regular maintenance and annual service calls.
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