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JD's Prompt Plumbing, Heating & Air Conditioning Blog

What Is Short-Cycling and Why Is It a Problem?


Short-cycling is a condition that occurs in heat pumps, air conditioners, furnaces, and other HVAC systems. It’s one of the more common problems that can afflict a home’s comfort system, but it also has a tangle of possible causes behind it. Short-cycling is both a symptom of a problem and a problem on its own. 

In this post we’ll go into detail about short-cycling, why you want it stopped, and why it happens.

The Basics of Short-Cycling

An HVAC system is said to be short-cycling when it isn’t completing a regular cooling/heating cycle but instead shutting down early, only to turn back on again a brief time later and repeat the process. This constant starting and stopping traps the unit in its start-up cycle, and that has several major consequences.

The Troubles With Short-Cycling

  • Increased wear and tear: Rapidly starting and stopping isn’t good for a heating or cooling system. It puts extra strain on motors and accumulates wear and tear much faster. If an HVAC system is allowed to continue short-cycling, it will accrue extra repairs and will fail years before its estimated service life.
  • Higher energy bills: A heat pump, furnace, or air conditioner uses the most amount of energy when it starts up. If an HVAC system is short-cycling, it will start up multiple times per hour and consume more energy than normal. You can expect to see higher energy bills because of short-cycling.
  • Uneven comfort: Cutting off a heating or cooling cycle early doesn’t allow enough time for conditioned air to move through the ventilation system of a home. The center of the house may have the right temperature, but other rooms will have hot or cold spots.

The Sources of Short-Cycling

Along with the problems that short-cycling creates, the underlying cause of the short-cycling is often the worst problem. This is one reason it’s so important to call on experts to investigate the problem: there are many potential causes for short-cycling, and you need professionals to make the correct diagnosis and then apply the right repair.

Here are several of the more common causes of short-cycling. There are many others.

  • A clogged air filter: Leaving a dirty air filter in place will cause many troubles for an HVAC system, including short-cycling. Change the filter every 1–3 months to avoid this.
  • Leaking refrigerant: For heat pumps and air conditioners, short-cycling is often a warning that the system is losing refrigerant to leaks. Lost refrigerant will lead to overheating and the AC/heat pump shutting down early.
  • Faulty thermostat: The thermostat for the HVAC system may be sensing incorrect temperatures in the house, causing it to continue to shut the heater or AC off early. 
  • Oversized system: The HVAC system may have been incorrectly sized when installed. When the system is too large, it will change the temperature in the house so rapidly that the system will falsely register that the heating/cooling cycle is finished. 
  • Electrical issues: The control board may be faulty. This can occur in all types of heating and air conditioning systems, including gas furnaces.
  • System age: For an HVAC system that’s over its estimated lifespan, short-cycling might be a warning it’s time to have it replaced. 

For quality help with your cooling and heating in Levelland, TX, you can rely on our team.

JD’s Prompt Plumbing, Heating & Air Conditioning serves the Lubbock area. Contact us for prompt and thorough help with your heating system.

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