By Anne Fonda
During normal operation, your heating and cooling system cycles on when it gets a signal from the thermostat to start warming things up or cooling things down. It cycles off when the set temperature is reached.
A properly sized and operating system may only run for 3 to 5 minutes and be off for hours in mild conditions, or it may run for several hours with very short off cycles on hot days. The system cycling rates are based on the thermostat “cycles per hour” setting alongside the thermostat requested capacity (load value)
AC short cycling is an abnormal cycle, where your air conditioner or heat pump turns on and off much more frequently. We enforce a minimum run time of 3 minutes and a min off time of 5 minutes with compressor operation. The shortest cycle would be 7 minutes. This extreme short cycling is not possible unless there is a system issue (which means a hot house).
HVAC short cycling issues can affect your comfort, your wallet, and the health of your system.
Most people don’t time their HVAC system cycles. But you may notice the comfort impacts of your air conditioner short cycling. Your home may be cool, but humid and sticky. This is because the cooling system removes moisture from the air while it cools.
Short cycling disrupts humidity control. You may also notice uneven cooling and heating, which can also result from short cycling.
Short cycling means your HVAC system is working harder and less efficiently. This can mean increased energy consumption, and with it, higher energy bills.
Repeated short cycling leads to increased wear and tear on your HVAC system. This can lead to more frequent repairs as parts wear out and break down.
Heat pump or AC system short cycling has two main causes.
A malfunctioning thermostat can send a signal to your HVAC system to heat or cool at random times. You may need to replace a thermostat if troubleshooting doesn’t resolve the issue.
A thermostat positioned in an area that gets direct sunlight can turn off the heat or turn on the air conditioning, regardless of what the temperature is in the rest of the house.
Your thermostat should be installed in a central location, away from air vents and heat-generating appliances, and out of direct sunlight. Sometimes moving an improperly placed thermostat can resolve short cycling.
An improperly sized HVAC system can cause short cycling from the day it is installed. The wrong size heat pump or air conditioner may have been installed when an HVAC company failed to do proper sizing calculations and just replaced an old unit with a new one of the same size.
An oversized system will reach the set temperature too quickly, leading to short cycling and poor humidity control. A heat pump or air conditioner that’s too small may struggle to cool your home. This can lead to “long cycling” rather than short cycling. Whether too big or too small, an improperly sized system can cause early wear and tear as well as high energy bills.
Unfortunately, the only permanent whole-house solution is to replace the system with a new, correctly sized HVAC system.
If you think your HVAC system is short cycling or you have inadequate cooling, contact your local Trane dealer for troubleshooting and expert solutions.
Anne Fonda, Content Writer
A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.
She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism.
When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.
Expert review by Eric Weiss, Technical Trainer
Air conditioners remove heat and humidity from the air in your home and place it outside to reach your desired indoor temperature. Central AC cools your entire home, while ductless AC cools just one portion or room in your home.
Heat pumps are HVAC systems that can perform both heating and cooling functions without the use of electric heat or fossil fuels.
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