AC Short Cycling: What It Is & How to Fix It


Does your home’s air conditioner turn on and off constantly? It may be short cycling – a common HVAC problem that can lead to complete AC unit failure. Not only is AC short cycling annoying, but it’s also expensive! Luckily, you can prolong your air conditioning’s lifespan by learning the causes of short cycling, how to stop it, and how to prevent it from happening in the future.

images of an AC handler

What is AC Short Cycling?

AC short cycling is the HVAC term for cooling cycles that are shorter than they should be. Air conditioners normally undergo three cooling cycles per hour on a hot day, each lasting approximately 10 minutes. So, the compressor will run for 10 minutes, stop for 10 minutes, and repeat the cycle two more times during a single hour.

Short cycling disturbs the cooling cycle’s pattern. When cooling cycles are shortened, the compressor turns on and off more than it should, putting extra stress on the compressor and damaging the entire air conditioning system. This excessive stopping and starting also prevents the air conditioner from effectively cooling your home.

What Causes My AC to Short Cycle?

Short cycling can happen as a result of multiple air conditioning problems:

  • Low refrigerant: Your AC’s refrigerant should remain at a set level, also called the charge. Insufficient refrigerant levels cause the air conditioner to work harder, leading to overheating and short cycling.
  • Failing compressor: A failing air conditioner compressor short cycles if it’s unable to stay on for a longer period of time. Short cycling further damages the compressor, so it is important to have an HVAC professional check it as soon as possible.
  • Oversized unit: If your air conditioning unit is too large for the size of your home, short cycling is likely to happen. Due to their capacity, oversized air conditioning units cool the space quickly and shut off in a short period of time, cutting off the full cooling cycle.
  • Frozen or dirty evaporator coil: Evaporator coils remove latent heat from your house. When they’re icy or dirty, they malfunction and overheat your AC system, causing it to short cycle.
  • Miscalibrated thermostat: A miscalibrated thermostat incorrectly gauges the specific temperature, causing the unit to turn on and off at the wrong time. The system shuts off prematurely and then quickly turns back on in an attempt to reach the set temperature.
  • Failing low-pressure control switch: This switch turns off the compressor when the amount of refrigerant in the air conditioning system falls below a specific point. When it fails, it produces short-cycling symptoms that affect the rest of your air conditioning system.

How Do I Fix Short Cycling?

Regular HVAC maintenance is the most effective way to prevent short-cycling issues from happening in the first place. Existing short-cycling problems can be resolved by an HVAC professional and, in some cases, may even be simple enough to do yourself! Depending on the root cause of your short cycling, here are some ways to get your unit’s cooling cycle back on track.

  • Check your air filter: A clogged air filter causes all kinds of problems for your HVAC system, including short cycling. If your filter is caked with dust and debris, replace it with a new one to prevent additional stress on your home’s system.
  • Check your thermostat: Your thermostat should be installed in a central location on an inside wall of your home. Ensure your thermostat isn’t too close to the return air register so it doesn’t get confused by the influx of cool air and produces the wrong readings.
  • Check your refrigerant levels: It’s a good idea to have a trained professional check the levels and, if necessary, add more refrigerant. Your HVAC professional will also track down any leaks within the air conditioning system.
  • Replace your low-pressure control switch: If you are still dealing with short-cycling issues after checking all the above, you should have your HVAC professional replace this component with a brand-new one.
  • Check the compressor: A failing compressor can exhibit symptoms of short cycling. It’s a good idea to have your HVAC professional check your AC compressor and, if necessary, replace it with a new one.

Schedule Your HVAC Service Today

Don’t wait until your HVAC system fails! Regular HVAC maintenance ensures that normal wear and tear doesn’t shorten the lifespan of your system. The sooner you schedule system repairs, the sooner our HVAC technicians can come to fix the problem, saving you from more extensive repairs in the future. 

The Big Dog in Heating & Cooling

Chancey & Reynolds has been installing, maintaining, and repairing HVAC systems in greater Knoxville since 1978. Our NATE-certified technicians determine precisely what your heating and cooling unit needs for optimal performance and a longer lifespan. HVAC users across Knoxville and Lenoir City trust our team of air specialists to keep their homes comfortable all year long. Contact us today to get started!