Air Conditioner Won’t Shut Off | AC Keeps Running

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If you’ve noticed that your air conditioner doesn’t turn off, don’t worry.

An air conditioner not shutting off is actually a pretty common problem air conditioner owners encounter. 

While it can be a real nuisance and something you need to fix, it doesn’t necessarily mean your air conditioner is broken.

You might not even need to call a professional to fix it. You could do it yourself.

Having said that, if your AC continuously runs without shutting off, you could have a more serious unit fault that needs fixing by an experienced HVAC. 

While this seems quite daunting, there are a number of relatively easy things you can do to try and solve the problem.

To help you, in this post, we will take you through the different reasons why your AC might not be shutting off, and how the problem can be solved.

If you’re experiencing problems with your air conditioner (see also our guide to cleaning your air conditioner drain) not shutting off, be sure to stick around!

Why Is Your Air Conditioner Not Shutting Off?

There are a number of different reasons why your air conditioner unit might not be shutting off (see also ‘Air Conditioner Keeps Running When Turned Off? Here’s What To Do!‘). For starters, it could simply be down to the weather.

When the weather outside is scorching hot, the air conditioner (see also ‘What Temperature Should I Set My Air Conditioner In Summer?‘) unit could be running slower.

The unit might also be running a lot more as it tries to compensate for hotter temperatures. This just goes to show how common this problem can be.

While this is quite a common reason for an air conditioner (see also ‘Outside AC Unit Not Turning On’) unit not shutting off, there are others, some of which are more serious, and others that are fairly similar in severity.

The other reasons why your AC might not be shutting off include a faulty thermostat, the wrong fan settings, a short circuit, or a malfunctioning relay switch. 

If you’ve noticed your air conditioner not shutting off, and have also identified one of the above problems, you’re in the perfect place.

These are the problems we will be looking at next, as well as details regarding how to solve them. 

Broken Or Damaged Thermostat

If you find your air conditioner just isn’t shutting off, a possible explanation is a broken or faulty thermostat.

A good way of spotting if you have a faulty thermostat or not is by checking your home’s indoor temperature.

If your home’s indoor temperature is lower than the setting you have selected on the AC thermostat, the thermostat isn’t functioning correctly. 

This could mean your thermostat is having difficulty working out the temperature in the room. As a result, the AC unit (see also ‘Here Is What To Do When Your AC Blows A Fuse‘) might continuously run when it shouldn’t. 

Sadly, there isn’t too much you can do about a faulty thermostat.

It is worth calling an HVAC technician to see what they think, but you are most likely going to have to buy a new thermostat.

The Wrong Fan Setting

Something as simple as having the fan set to ON instead of AUTO on your thermostat could cause the AC to continuously run without shutting off.

Luckily, this problem is usually very easy to fix. 

AC fan’s generally run separately from your air conditioner unit (see also ‘Air Conditioner Running But Not Lowering Temperature‘). The two different systems work together to make the home comfortable.

They do so by providing fresh, clean air. The problem with this is that when they work out of sync, issues can arise.

An example of this is when the AC keeps running and the fan shuts off. 

By having the AC fan set to ON, your fan will run continuously, even when your AC system has shut off. This is why you should ensure the fan is set to AUTO.

By setting the fan to AUTO, whenever the AC system is running, so will the fan. On the other hand, when the system is off, the fan shuts off too.

You can easily identify this problem by taking a look at your thermostat. If the fan is set to ON instead of AUTO, simply change the setting. 

Hot Temperatures Outdoors

Hot Temperatures Outdoors

If you find yourself dealing with air conditioner problems halfway through July, it could simply be down to the fact the weather is super hot outside.

In locations with soaring summer temperatures like Texas and Arizona, this really isn’t uncommon.

When the temperature gets too hot, AC systems can have trouble trying to keep up.

You can easily work out if the outside temperature is the problem by turning the temperature on the thermostat up by 10°.

If the unit powers down, this is a sign your air conditioner unit is far too small for the size of your home. 

If an air conditioner system is too small for a house, it will struggle to match the demand.

This can result in the unit running continuously without shutting off. The system will continue to run after the power has been turned off.

The only way to fix this issue is to purchase a new system. A professional will help you find the air conditioning system that better suits your home.

Relay Switch Malfunction

Your air conditioner system might not be shutting off because you have a malfunctioning relay switch.

A relay switch opens and closes the electrical circuits that run through the air conditioner.

This includes the fan. As your air conditioning system gets older, it isn’t uncommon for these relay switches to get damaged or stuck due to general wear and tear. 

This can result in a lack of communication between the air conditioner’s fan and thermostat.

This can then lead to the AC not shutting off when you try to turn it off. Most of the time, the fan will continue to operate. 

If you have good electrical experience, you could solve this problem yourself by replacing the relay switch.

If you don’t have any electrical experience, we strongly recommend getting a professional to do the job for you. They will know exactly how to fix this problem safely.

Short Circuit

The final culprit in this post is a short circuit. When your AC system has a short circuit, whatever you do on the thermostat probably won’t work.

The reason for this is that the short circuit causes the system not to recognize your chosen settings. This will lead to your air conditioner not knowing how to adjust.

Therefore, when you decide to set your thermostat to OFF, the message won’t get to the system. 

If you find that air continues to run through your AC system when it has been turned off, one of the most common problems could be a short circuit.

You will need an experienced HVAC to solve this problem. With that in mind, you should probably give the professionals a call.

Final Thoughts

Fixing an air conditioner system that won’t shut off can seem like a daunting task, but in reality, there isn’t too much to worry about.

AC systems might not shut off for a number of reasons, some of them pretty simple to fix, while others require a professional.

If you do experience any problems with your air conditioner not shutting off, the most important thing to do first is not to lose your patience.

These problems are fairly common amongst homeowners with AC systems, so never stress that your air conditioner (see also ‘What Is An Air Conditioner Pad?’) is broken. 

Your AC unit (see also ‘How To Put Freon In An AC Unit: Everything You Need To Know‘) might just be struggling because of the outside temperature or because you’ve accidentally chosen the wrong settings.

If these factors are the case, they can be easily solved by yourself.

Even bigger problems such as a faulty thermostat or malfunctioning relay switch don’t need to cause you too much concern.

A professional with air conditioning experience will be able to fix the problem with little trouble.

Now you understand why your AC might not be shutting off, take some time to work out the cause of your problem.

You can then take the necessary steps to fix the issue. 

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