AC Won’t Turn Off? Find Out Why and What to Do

When your AC is constantly running and is not keeping the space cool, it should be cause for concern. AC units that won’t turn off can waste electricity and increase your utility bill. An AC that is constantly running usually results from a malfunctioning component which may be anything from a frozen evaporator coil or a dirty air filter to a bad relay switch, the fan blowing constantly, or a bad thermostat. Take a closer look at what to do when your AC is always running and how you can fix the problem. Remember, it is usually best to contact your local Trane expert when it comes to AC repairs.

It’s important to watch how often your AC unit is running a cooling cycle. If the AC unit or fan runs continuously, there may be a problem which needs to be investigated. There are several factors that may cause your indoor or outdoor AC unit to run continuously.

Thermostats are not meant to last forever and should be replaced over time if you are experiencing issues. Over time, sensors can attract dirt, electrical wires can be damaged, and wires can become loose – interfering with the connection between the thermostat and the AC unit. If this is the case, your thermostat will need to be replaced. Additionally, incorrect thermostat settings may lead to a fan constantly running, which may feel like the AC unit is running. When the fan setting is set to ‘on,’ the blower motor and fan will run, but not the actual AC unit. You will hear the indoor blower motor running and may feel air out of the vents, but the air temperature will not be cool. 

Air conditioning runs on electricity, and the unit has several electrical components. If the compressor contactor becomes welded closed, the AC unit will continue running with constant power. Because this is an electrical issue, you need to call a professional to replace the faulty switch.

Homeowners should replace air filters every 30-90 days, depending on the size of the home, the number of pets, smokers, and allergies. Dirty or clogged air filters are often behind most issues homeowners face with their air conditioning units. A dirty air filter can cause inefficiencies in your cooling system, making cooling cycles longer to complete. If left unchecked, dirty air filters can cause long-term damage to your AC unit.

To keep your AC unit functioning efficiently, the evaporator coils in your indoor air handler unit should be kept clean. Cooling cycles may become prolonged if these coils become clogged with dirt or debris, and your vents may start blowing warm air. It is best to have an HVAC professional clean evaporator coils as there is a risk of electrical shock. The coil fins are easy to damage and a homeowner can actually do more harm than good as many household cleaning products will either damage the copper or aluminum, or will initiate a corrosion issue. An HVAC technician has the products and expertise to clean the coils safely.

When your air conditioner is constantly running, it may be because your AC unit is too small for your home. If the unit is too small, it will be working overtime to achieve the set temperature in the house, and will wear out faster. A professional Trane dealer can help you determine the correct AC size for your home. The dealer will consider not only the square footage of your home, but also construction and insulation materials, ceiling height, amount of sunlight, and how many people live in your home. Air conditioners are sized by British Thermal Units (BTUs). A one-ton air conditioner is rated at 12,000 BTUs and a five-ton air conditioner is rated for 60,000 BTUs. The larger the home, the larger the BTU requirement.

It is normal for your AC unit to run longer than usual in the hottest months. A normal cooling cycle lasts approximately 20 to 30 minutes, and your unit should complete two to three cycles each hour.

If your AC unit runs continuously, it’s usually a result of a system issue. This wastes electricity, driving up your power consumption and increasing your energy bill. It can also cause wear and tear on your AC unit, leading to inefficient operation and rising repair costs.

At some point, even the most dependable units will need replacement. Contact your local Trane expert if your AC unit won’t shut off and you can not fix the problem yourself. A dealer will come to your house, inspect your unit, and determine what is causing the AC not to turn off. It’s better to call as soon as you realize the unit is running continuously. Waiting to fix the problem may cause the unit to burn out and result it in needing to be replaced instead of simply repaired.