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Why Does My Air Conditioner Keep Turning Off Too Quickly?

On a hot day, you might need the air conditioning a lot. However, if you start to notice that the cool air shuts off too soon, you might have a problem. Air conditioning units that cycle too frequently and quickly are said to be “short cycling,” which can have an impact your home comfort, energy efficiency and the lifespan of the equipment. Follow these tips to solve the problem and prevent it from happening again.

Common Cause of Short Cycling

There are a number of reasons that your air conditioner might be short cycling, but a few are more common than others. These concerns may require repair or replacement:

  • Evaporator Coil Issues: The evaporator coil removes heat from the indoor air and allows the blower to circulate it again. If the coil gets dirty, condensation can collect and freeze on the coil. The system works harder to thaw the coil, but shuts off quickly due to overheating.
  • Refrigerant Problems: Low refrigerant is also a common cause of a frozen evaporator coil. The refrigerant is converted from a vapor to a liquid and back again as part of the process of removing heat. Low refrigerant due to a problem with metering or a hole in the refrigerant line may disrupt the cooling system, prompting short cycling.
  • Poorly-Sized Air Conditioner: Air conditioners are measured by their output. If you have a unit that is too big for the cooling load you place on it, the air conditioner will reach the set temperature too quickly and turn off. While this may seem like a benefit, it actually taxes the equipment and can provide you with ineffective cooling.

Negative Effects of a Short Cycling Air Conditioner

It is quite possible that an air conditioner could be short cycling for weeks or even months without breaking down in a way that is obvious to you. Here is what you can expect from a
system that is short cycling, if you do not identify and solve the problem quickly:

  • Increased Humidity: You may not know that air conditioners were initially designed to remove humidity from the home as much as heat. An air conditioner that is too big for the home may easily be able to achieve the right temperature, but fail to run long enough to remove humidity. This leaves your home feeling muggy and makes the space a more inviting environment for mildew and mold.
  • Higher Energy Expenses: Every time the air conditioner turns on, it uses energy. The more it turns on, the more energy used. As a result, a short cycling air conditioning unit is likely to increase your energy bills. Since short cycling is not considered an efficient use of the machine, you might pay more to feel less comfortable.
  • Worn Components: You can typically expect about 10-15 years, or even 20, out of your air conditioner if you get regular maintenance and prompt repairs for it. However, just like your car, it depends on the miles you put on it. Running your air conditioner into the ground with short cycles will wear out the compressor much more quickly, which is one of the most expensive components of the unit.

Preventing Short Cycling

The best defense is a good offense—and one that helps keep you comfortable throughout the summer. Unless your air conditioner is simply not working at all, you may not realize that it is struggling until significant damage or wear has already occurred. The possibility of short cycling underscores the importance of sizing your air conditioner properly and getting regular maintenance once you have it installed. Air conditioning units should be selected based on the ideal size and output for a particular home.
This is difficult to do without expertise, because there are so many factors involved, including:

  • The amount of insulation in your home
  • How many people live in your home
  • The climate of your region
  • The size and style of your home
  • The efficiency of other systems within you home

In short, you cannot just calculate the square footage of your home and know how many tons your air conditioner should be. You may short or overestimate your needs, and both situations have problems.
After you have an HVAC technician estimate your cooling needs and install a new air conditioner for you, it is absolutely crucial to get regular maintenance and repairs when you notice something is not right. Refrigerant leaks or a frozen evaporator coil might not be easy to see with an untrained eye. Experts know how to look for these issues, and can often prevent them.
An air conditioner that is constantly short cycling is irritating and can make your summer much more uncomfortable. By getting the right size air conditioner and taking care of it properly, you can stop short cycling from costing you in money and comfort.