Why Does My Air Conditioner Starts Then Stops after Only a Few Seconds? (And How to Fix it)

Have you ever gone home after a scorching day, turned your air conditioner on to enjoy a nice breeze -and after a few moments, everything just shut down randomly?

“My air conditioner starts then stops after only a few seconds;” this statement has brought sadness to many homeowners looking for some cool air. Thankfully, there are ways for you to find out right away what’s going on.

Air Conditioner Starts Then Stops After Only A Few Second

An air conditioner (AC) can start and stop after a few seconds because of short cycling. Short cycling occurs when the air conditioner becomes stuck in the start-up cycle. And the AC compressor stops prematurely. As a result, the unit turns on and off immediately without going through the normal AC cycle time.

Reasons Your Air Conditioner Starts then Stops After Only a Few Seconds & How to Fix It

Here are the most common causes of short cycling –  along with a few quick fixes to get it back working again.

  • Low Refrigerant

Your air conditioner’s compressor is supposed to have refrigerant liquid in it. During the air conditioning process, that refrigerant goes from liquid to gas and then condenses into liquid. This transformation cycle will absorb the heat in the air and cool it.

If your unit is low on refrigerant, then it might be that you are facing a leak. In this case, it messes with your compressor’s pressure control – causing it to reset itself continually.

If you believe that there’s a leak, then you’ll have to call a professional in the field to help.

  • Thermostat Problems

It might seem obvious, but if your air conditioner is short cycling continuously, the chances are that there might be something wrong with your thermostat.

It might seem like the thermostat is the least important part of the AC unit, but it controls the entire temperature in your home. It sends a message towards the heat pump or the air handler, therefore regulating the temperature. This is why it must function correctly.

When the thermostat does not accurately sense the room’s temperature, it might deliver the wrong message to your air conditioner. As a result, your AC system will start and stop continuously.

Check whether the screen of your thermostat is fading or even goes blank. If that’s the case, then it may be running low on power or intermittently losing power.

When the thermostat loses battery, it will confuse the AC unit and cause it to turn itself on and off continuously. A quick fix would be a change of batteries.

  • Dirty Air Filter

A dirty or clogged air filter is often the bane of air conditioners and the one causing the most problems. Since the airflow is compromised, it can lead to a fair number of problems – one of them being short cycling.

Fixing a dirty air filter is quite easy: you either need to replace or clean it, depending on whether you have a reusable filter or not.

  • Bad Run Capacitor

The run capacitor of your air conditioner gives the unit its energy boost to turn itself on. It is also the part that ensures the AC system stays on while needed.

If this part begins to malfunction, it can end up sending intermittent power to the HVAC system – which won’t be enough to keep it running. If your outside air conditioner behaves like this, then the problem is likely the capacitor – in which case, you need to contact an HVAC service.

  • Dirty Condenser Coils

If your AC system refuses to stay on, then you may have a bit of a problem with dirty condenser coils. If you haven’t performed maintenance in a long time, you might expect short cycling because of this.

Without cleaning your AC regularly, your air conditioning system may be packed with dirt. The condenser coils are located in the outside unit, releasing heat gathered from inside.

When air conditioners gather too much grime around the coils, they can overheat and continuously shut down the air conditioner. You can fix this short cycling hitch of your air conditioner by cleaning the compressor coil or hire an HVAC service.

  • Over-Sized Air Conditioner

Did you always have this problem? Or did it only start when you installed your glorious new air conditioner? Well, it may look pretty, and it may promise a lot of cool air – but an oversized air conditioner can also cause a problem.

To put it simply, if the system is too large, then it may not have the correct refrigerant cycle. In the end, an oversized air conditioner will face issues such as cooling your home too quickly and then shutting itself off immediately.

This might seem like a good thing – only, it’s not. Your home will not cool down evenly, and your AC will have to turn itself on and off chaotically. This is why you may want to see a technician to ensure you get an air conditioner in the correct size.

  • Frozen Evaporator Coils

If the thermostat is working well and you conduct regular maintenance on your air conditioning unit, then it might be that you are dealing with a frozen evaporator coil. This often happens when you have a refrigerant leak or issues with the airflow.

Depending on the conditions, you might need to consider AC repair. An HVAC professional should fix any problems with the outside unit, particularly if the issue is a leak of the refrigerant. Check the air filter first, as this is often something you may do yourself.

  • Refrigerant Leak

When you experience a refrigerant leak, it might cause your outside unit to be low on refrigerant. Because of this, the low refrigerant will continuously send the air conditioning system into short cycling periods of about 15 minutes at most.

Refrigerant is essential, as the motorcycles it through your AC unit, absorbs the heat, and allows you to reach the temperature set on the thermostat. And if there are any holes within the system, the refrigerant will leak.

This can cause various problems such as low pressure, faulty compressor – and obviously, short cycle issues. This is why you need to have an AC repair professional see your air conditioner. They have the rights reserved to fix any complicated problem in the shortest time possible.

  • Electrical Problems

If you are not low on refrigerant and your air conditioning system receives regular maintenance, you might be dealing with electrical problems. Short cycling is often caused by bad wiring from the thermostat or any other electrical problems.

To fix this issue, you may need to call in a professional. An electrician will have the experience to solve these kinds of situations, and they’ll be able to spot the problem from the moment the air conditioner turns on (or doesn’t).

If the thermostat or the wiring towards the compressor or fan is broken, they will know how to replace or put things back together – therefore, stopping the short cycle.

  • Bad Thermostat Placement

Short cycling can also be caused by something as simple as the wrong placing of the thermostat. Since the thermostat is the one that determines whether a room needs cooling or not, a cool breeze or something like that can cause inaccurate readings.

The messages it sends to the compressor or other air conditioner parts are inaccurate, so it no longer turns on when you need it. If you don’t want your air conditioner to turn on and off, refrain from placing the thermostat in the following places:

  • Close to a window or in a place that is exposed to direct sunlight.
  • Near a room that is much warmer compared to your home (for example, a bathroom or a kitchen)
  • Under the supply air vents, as it will turn on because of the cool airflow.

Your air conditioner turns on and off as it reads the temperature around. If you have the thermostat in one of the places mentioned above, you might want to put it elsewhere. If it sits in the wrong room, it might confuse the air conditioner and cause it to deliver heat rather than cool air.

Other related air conditioner problems:


There are various explanations why an air conditioner turns on and off after only a few working minutes. You might be dealing with a faulty thermostat, problems with the compressor, leaks, or any other similar problems.

In most cases, the issue is the thermostat, poor maintenance, or a refrigerant leak. With that in mind, you should always call a professional to fix the problem, as they have enough experience to come up with a proper solution.

I hope this article on ‘air conditioner starts then stops after only a few seconds’ was helpful. Leave us a comment under this post and tell us about your experience.



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Ronald Watford, the owner of Quality Home Air Care, is a qualified HVACR technician and manages the team of expert writers on this site. He believes that educating homeowners about HVAC systems is one of the most impactful aspects of his job.