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My AC Is Short Cycling: What Is Going On?

A white living room with a beige couch

When you turn on your air conditioner, you expect your home to become a cool and comfortable reprieve from the outdoors. This is why it would come as quite a surprise if you hear your unit shut off quickly after turning on, even though your home isn’t cooling down. After this happens a few times, you’re probably wondering what is going on and what you can do about it.

Before we get into what might be causing this to happen, it’s important to be able to recognize what is considered short cycling and what is considered normal for a typical cooling system. The cycle on a properly-working air conditioner should be roughly 15 to 20 minutes, and your system will run two to three times each hour. In very high temperatures, the cycle will be longer as the AC tries to get the home down to the correct temperature.

Short cycling, in contrast, causes your system to run for a little while and then shut off before the temperature gets down to where you want it. That leads to the unit turning back on just a little while later. Then, the cycle repeats. The result is that your house is never quite the right temperature, your energy bills are higher and your unit puts itself through a lot of unnecessary wear and tear.

There are several reasons you might have an AC that is short cycling. Identifying the reason why will help you determine whether this is a problem you can try to address yourself or whether you’ll need to contact a specialist.

AC Unit Is Too Big

In some cases, you may have a problem on your hands that is quite difficult to resolve: your AC unit may be the wrong size for your house. Bigger is not always better, and an overpowered system will blast cold air for just a few minutes and then shut off. This leads to a house that alternates between too cold and too warm. Unfortunately, the only solution for an incorrectly-sized AC unit is to remove it and install a new, appropriately-sized system. If you find yourself in this situation, contact a reputable provider to perform a load calculation to make sure you’re not being oversold on a system that won’t work and will waste energy.

Dirty Air Filter

Another, easier to remedy answer to why your air conditioner might have started frequently turning on and off again is that you have a dirty air filter. If your filter is dirty, your AC unit has to work harder to pull in air, which can lead to your compressor overheating and shutting off. Then, when your thermostat tells your unit that your home isn’t cooled to the desired temperature, it will turn back on again. However, the restricted airflow coming through your unit will lead to your compressor overheating again and shutting back off. Your air conditioning unit will continue cycling like this, putting additional strain on your system and bringing up your energy bill, until you change your air filter. You can check your filter to see if it’s clogged or dirty and, if it is, replace it with a new filter.

Frozen Evaporator Coils

Another reason for short cycling is frozen evaporator coils. If your AC unit isn’t working properly, its evaporator coils can develop a coating of water that freezes over time. That makes it difficult for your AC unit to remove heat and moisture from the air effectively. Your unit will work harder in an attempt to cool your home until it overheats and shuts off for its own safety. To prevent further problems, shut off your air conditioning unit until a specialist arrives. There are a variety of reasons why your evaporator coils might freeze up, so you’ll need professional assistance to diagnose the root cause of the problem and make any needed AC repairs.

Generally, you can prevent problems that lead to frozen evaporator coils by performing routine air conditioner maintenance. If you don’t feel comfortable maintaining your own unit, you can schedule periodic visits with a professional who can perform this task for you.

Refrigerant Leak

If there’s a refrigerant leak in your system, your AC unit won’t have the key ingredient it needs to actually cool the air. Like frozen evaporator coils, your unit will have to work harder to pull the heat and moisture from the air, which will cause your system to overheat and short cycle. Left unchecked, this situation will also waste energy and potentially damage the unit’s compressor over time.

Electrical or Wiring Issues

Electrical problems can also result in short-cycling if they negatively impact the function of your thermostat. When this happens, your thermostat may send the wrong signals to the unit, causing it to turn on and off erratically. If wiring is the problem, you’ll likely want to contact a specialist to make electrical repairs.

If your unit is short cycling, often the easiest way to properly resolve the problem is to contact a licensed professional. A trained technician will be able to determine what has gone wrong and recommend any necessary AC repairs.

As we’ve already mentioned, before you call in an expert, you’ll want to check your air filter is free of dust and other debris.

A man replacing a dirty air filter with a clean one

AC Filter Is Dirty: How Often Should I Check It?

A dirty AC filter is the easiest problem to prevent, but dirt builds up more quickly than you’d think, and there are many different considerations that you should take into account when creating your filter maintenance schedule, including the type of filter you have in your home. Typically, pleated air filters should be replaced once every three months, while less expensive fiberglass filters should be changed once a month. Some high-end pleated filters can last as long as six months. Reusable filters with either metal or plastic frames can be cleaned when dirty with a vacuum or warm water spray. If you opt for using water to clean your filter, just make sure to let the filter dry before reinserting the filter into your unit.

There is not one hard and fast rule about how often you should replace your filters, but there are several factors to keep in mind that may dictate how fast dirt, dust and debris will accumulate. One thing to take into account when determining how frequently you should change your filter is the number of people in your household. If anyone in your home has allergies or asthma, if you have pets or if you have younger children, you should change your filters on a more frequent basis.

Furthermore, you should also consider how often you use your system and the size of your house. Someone who runs their air conditioning unit all day, every day will need to clean or change their filters much more routinely than someone who only runs their unit for a couple of hours every day or even every few days. Also, those living in a smaller home will likely have to change or clean their filters less frequently, as smaller homes require less air to flow through the filters to appropriately cool the home.

Aside from short cycling, you may experience any of the following issues if your filter is dirty:

Fortunately, it is pretty easy to determine whether your filters are dirty. If your air filter looks dirty, dusty or damaged, go ahead and switch it out for a new filter or clean it. If you’re still having trouble determining the right AC filter maintenance schedule, you can try scheduling an appointment with a heating and cooling specialist who can advise you on the best schedule for your home, as well as provide you with any other tips on how to maintain your AC unit.

We had also mentioned that an AC unit that is too big or too small can lead to a unit that turns on and off repeatedly. Unfortunately, as a homeowner, it can be difficult to determine the correct unit size for the home, and many times we can incorrectly assume that bigger means better.

An air conditioning vent

What’s the Right AC Size for a House?

Getting the right size AC for your home is key to having a comfortable indoor environment. A system that’s too big or too small will waste energy and begin to have problems before it should. There’s a sweet spot in size for every home. Don’t let yourself get caught in the misconception that bigger is always better when it comes to your heating and cooling system.

The most precise method for figuring out your home’s cooling needs is the Manual J report. This calculation involves a variety of different factors, including the square footage of your home, the climate zone you’re living in, how many windows you have, how many people live at home and how many heat-generating appliances you own.

However, there are rough estimates of how much cooling power your home will need based on square footage. You can use these numbers as a baseline so you have an idea of how many BTUs your new unit will require:

  • 23,000 BTUs for a 1,200 to 1,400 square foot home
  • 24,000 BTUs for a 1,400 to 1,500 square foot home
  • 30,0000 BTUs for a 1,500 to 2,000 square foot home
  • 34,000 BTUs for a 2,000 to 2,5000 square foot home

If your unit is too big for your home, it can cause more problems than just short cycling. An overpowered AC unit will check the temperature from the main thermostat. If the desired temperature does not match the indoor environment, a short blast of cold air will enter and cool the room to your preferred temperature, but leave other rooms too warm. If you notice that your home is uncomfortable in some rooms but fine in others, your AC unit might be too big.

Another symptom of an improperly sized system is that your home may be humid even if it’s the right temperature. A cooling system is designed to remove moisture from the air, and this process takes time. If your AC unit cools your home to the right temperature too quickly, it won’t have time to remove humidity. That can lead to mold, condensation and a sticky feeling inside.

Finally, your electricity bills will likely be just as oversized as your AC unit if the system has too much cooling power. A bigger unit draws more power, even when it’s not being used efficiently. High energy bills are a sign that you have a problem. If you suspect your system is not appropriately sized, reach out to a heating and cooling specialist. Licensed professionals can run diagnostic tests and perform the right calculations to determine what type of system is best for your needs.

ABC Can Keep Your Home Cool and Comfortable 

Air conditioning units are complex and have many different parts that must work in harmony in order for your system to function correctly. If something goes wrong, you can rely on the licensed specialists at ABC Home & Commercial Services to quickly diagnose and make any AC repair you may need. As a full-service heating and cooling provider, we offer everything from routine maintenance to emergency repairs to consultations for a new system.

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