How to Stop an Air Conditioner From Short Cycling: Differential Thermostats

By | June 16, 2019

How to Stop a Air Conditioner From Short Cycling Differential Thermostats

If your air conditioning unit is turning on and off constantly it is doing what is called Short Cycling.

A unit that is short cycling can cause wear and tear on a unit leading to expensive repair cost.

An electricity bill will also be higher since a compressor in an air conditioner uses more power when it starts.

Air conditioners compressors run more efficiently after they have been running for a few minutes as compared to first starting up.

Factors that can be the cause short cycling include refrigerant levels, thermostats, over sized units, or homes that are not well insulated.
Thermostats Set with a Larger Differential Range
One of the things often over looked is a thermostats differential range which is the temperature a thermostat will turn a unit on or off.

Many thermostats have a +-1 to +-3 degree thermostat differential range.

For example, a thermostat with a +-1 degree differential set at 70 degrees will turn off an air conditioner at 69 degrees and on at 71 degrees.

This works fine in a home that is well insulated with an A/C unit properly running and sized to a home.

But what about a home that may need to be better insulated or have over sized units?

A thermostat with a wider differential range can help save on wear and tear of components and electricity cost.

Ideally solving the core of the problem is the best option but it can be expensive to replace an air condition unit or add more insulation to a home.

If you are having problems with a short cycling unit talking to a HVAC technician would be the first step.

If you have the money to solve the core problem than this is the best option.

For a cheap and easy, short time solution using a wider differential range thermostat can work in a pinch.

You may already have a thermostat that can change the temperature on off range.

To see if it is capable Google it or finds its manual and check what setting it has.
A differential range thermostat can help a short cycling air conditioner greatly by giving it a wider temperature range for starting and stopping.

The root cause of the short cycling should be identified and a plan to fix it should be done.

For a quick, cheap and easy short term solution the right thermostat can help greatly.

Category: Thermostats for heating and cooling

About Aaron H. Benetti

Aaron H. Benetti an HVAC technician who has worked in the field since 1991. He began his career as an HVAC installer and later began doing troubleshooting and repairs. Around 2010, he began to write books on HVAC topics, mainly tutorials and how-to information. Currently, Aaron works as an HVAC tech and also writes many articles and posts for websites as well as books and videos on HVAC topics.

4 thoughts on “How to Stop an Air Conditioner From Short Cycling: Differential Thermostats

  1. James A Rogers

    i want one that will turn on to cool at 75 and turn off at 70 that way to give the unit a rest in this texas hot heat nobody make this this 1+ and 1- is a POS.. they make these to kick on and kick off to burn up you unit so you can go out and buy a new one..

  2. Jeff Zeidler

    Just replaced a 10 year old 5 ton heat pump with a 5 ton . Nothing but problems with the old one since we bought the house 2.5 years ago, a lot of Freon leaks, and other issues. After it was torn out, you could see the return coils were completely clogged (ran without a filter?). They replaced the old thermostat with a new one that has no temp differentual. New unit is quick cycling. I thought it was from the new thermostat, they are telling me I need to replace the 14″ trunks with 16″ even though there was no problem prior to getting the new unit. Can someone please give me some input before I spend money on the ducts, they told me 16 is a must with the 5 ton.

  3. Orren Shumaker

    “For example a thermostat with a +-1 degree differential set at 70 degrees will turn on a air conditioner at 69 degrees and off at 71 degrees.”

    THIS SHOULD ” For example a thermostat with a +-1 degree differential set at 70 degrees will turn on a air conditioner at 71 degrees and off at 69 degrees.”


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