Why Does My Air Conditioner Keep Going on and off, Short Cycling?

Air conditioners work hand in hand with thermostats to ensure that you are comfortable at all times. During the summer, you house gets to heat up faster than normal making your thermostat to record high temperatures. The thermostat then sends a signal to the AC which has to cool the temperatures of the surrounding. If the AC does not behave, there is definitely a problem.

In most cases, the AC is not able to complete a full cooling cycle. It turns on for 2-5 minutes then turns off again. Your AC system is experiencing a short cycle. There are many reasons why this unit is short cycling and we discuss them in this article. Short cycling needs urgent repair because it may easily lead to you paying high energy bills or spending a lot of money on repairs if you let the problem go on for a while.

What is Short Cycling?What is Short Cycling

Short cycling is when the air conditioner’s cooling cycle stops prematurely because there is an obstruction. A full cooling cycle takes place when your AC turns on to the moment when the temperature you set on your thermostat reaches and then turns off again. So, if your thermostat goes off before completing this cycle, there is a short cycle.

Notably, an almost complete air conditioning cycle may last about 20 minutes. In these 20 minutes, the compressor will run for the first 10 minutes then stop for the last 10. In one hour, the cycle repeats twice. If your conditioner cannot manage to stay on for ten minutes, short cycling is taking place.

One of the common problems that emerges from your AC short cycling is high energy bills. This is because it keeps going on and off and it takes a lot of power to frequently power your AC again and again over a short period of time.

Moreover, the AC together with its parts can easily wear and tear thereby shortening its life cycle and you will have to cough up lots of money on unnecessary repairs.

Possible causes of Short Cycling and Solutions

1. Frozen evaporator coilswhy does my air conditioner keep going on and off

The only time you should run your AC is when it is hot. Running your air conditioner when it is cold may cause the evaporator coils in your AC to freeze. Also, in case there are any mechanical problems, the coils will definitely freeze.


Check for ice buildup on your outdoor AC unit or the air filters. Switch off the system and wait for the ice in the coils to defrost. If this does not help, contact a HVAC professional to help you out.

2. Oversized air conditionerOversized air conditioner

Before you purchase an AC, you need to consider the size of your home and where you want to mount it. It should not be too large for your home. A larger AC will be too strong causing it to deliver a lot of cold air (more than required) and thus short cycling. A large AC system will have an inaccurate refrigerant cycle thus there will be an uneven cooling.

Some of the problems arising from an air conditioner that is oversize include;

  • High chances of the air conditioner breaking down
  • Shortening of lifespan of your air conditioner
  • High electricity costs because an AC requires more power to turn it on.


Make sure you use an AC sizing calculator to calculate the size that appropriately fits your home.

3. Dirty air filter

Dirt may lead to your air filter clogging. A clogged air filter will block fresh air from getting through to the AC system. This will result in your system overheating making it launch before the cycle comes to an end.


Check your air filters frequently for any dirt and replace them when need be.

4. AC Wiring system

If the wiring system of your AC is incorrect, it may lead to short cycling. This includes damaged or rusty wires and control boards that are defective.


Take the necessary precautions and open up your air conditioner. Check if the wire terminals match correctly. But the most appropriate thing to do is call for professional help because you are dealing with electricity.

5. Leaking refrigerantLeaking refrigerant

If your air conditioner system is too low on refrigerant, a refrigerant leak is likely to occur. A refrigerant plays the role of a coolant that absorbs heat and cools down the hot air within your home. The refrigerant levels may be low because of some holes that allow it to escape.

Low refrigerant levels causes the compressor to break down, thereby shutting it off because of low pressure. Once the compressor is off, pressure will start rising and turn on the compressor again leading to a short cycle.


Refrigerant leaks are not something that you can sort on your own because they are dangerous. The best thing is to contact a HVAC company to come and take care of the leak.

6. Issues with your thermostat

Thermostats control the temperatures in your home. If your AC is experiencing short cycling, then there might be a problem with your thermostat. One problem is that the thermostat may fail to sense the temperature correctly and hence send wrong information to the AC which powers on and off often.

Further, if your thermostat is low on batteries it will cause your AC to start and stop frequently. Besides, there is the factor of thermostat differential range whereby most of them have a +-1 to +-3 range. This range only works with an appropriate size air conditioner. If it is oversize, the differential range may cause short cycling.


First, reset your thermostat and check if AC will work appropriately. If batteries are a problem, replace them with new ones. You can check the wiring as well. If all these solutions fail to work, call a professional to help out.

7. Positioning of thermostatPositioning of thermostat

There are specific positions in your home where you need to mount your thermostat for it to deliver the best results. Positioning of your thermostat largely affects its functioning because it measures the temperature of the surrounding environment.

If you place your thermostat next to a window where there is direct sunlight, near air vents, in the kitchen or near the door it will read inaccurate readings by the thermostat. This will lead to your AC turning on and off.


Ensure you place your thermostat in a good position, most likely in the interior wall of your living room.

8. Condenser coils are dirty

Short cycling of the outside AC unit may be due to dirty condenser coils. If you do not perform regular AC maintenance, you will not notice the dirt and debris accumulating in the coils. Dirt will cause your AC to overheat hence turning on and off frequently.


Clean the grime and dirt in your condenser coils or contact a HVAC company to come and perform maintenance on your AC.

9. Malfunctioned compressor

Your AC compressor may start overheating or fail to work altogether. This causes your AC system to go off habitually and then turn back on in a short while.


Call a local AC company to come and diagnose the problem with your compressor and do the necessary repair.

Impacts of Short Cycling on your AC systemImpacts of Short Cycling on your AC system

Short cycling is a serious problem that occurs in an air conditioning system. If it is not taken care of, it will result in dire consequences. Do you know that just turning on your air conditioner consumes a lot of energy? Yes it does.

Now, can you imagine how much energy it uses when it keeps going on and off and you have to keep turning it on? You will eventually have to cater for such high costs and this is not really economical.

Additionally, short cycling causes the compressor to overheat and it gets to wear and tear over time. Similarly, overheating may cause it to burn out. Repairing a worn out or a burnt out compressor is not budget friendly.

In other cases, you may have to replace the entire AC unit and this will cost much more and that is something you are not ready for at the time.

The most probable solution for short cycling is carrying out regular system maintenance on your HVAC unit. This is not something you can easily do on your own. Try looking for the nearest HVAC Company and get a professional to assist you with the maintenance.

Moreover, as soon as you notice short cycling, deal with it as soon as possible. Delaying may lead to more adverse effects. Nowadays, there are variable air conditioners that work by regulating the production of your unit instead of completely shutting it off. You should invest in such ACs.


Now that we answer the question “why does my air conditioner keep going on and off?” We are comfortable that you can tackle the short cycling issue on your own. If you cannot, do not hesitate to contact a professional. Keep in mind the common causes of short cycling and deal with them accordingly in order to restore comfort and save on huge energy bills.

Leave a Comment