Why Does My Air Conditioner Keep Running After It Has Reached It is Set Temperature?

An air conditioner is a literal godsend if you live in an area that gets hot during the year, but it can be frustrating when it malfunctions. When your AC unit continues to run after the set temperature has been reached, it’s natural to wonder, “why is this happening?” 

There could be several reasons why an air conditioner keeps running after it has reached the set temperature. The following issues could cause this issue: 

  • Dirty unit.
  • Improper temperature setting.
  • Mechanical issues.
  • Age.
  • Size of the unit. 

In this article, you will learn about why your air conditioner may be continuing to run after the set temperature has been reached, as well as some ways you can fix the problem.

Reasons an Air Conditioning Unit Runs Non-Stop

Once your home reaches the desired temperature, you can typically expect your unit to turn off. After all, this is the way air conditioning units are supposed to operate.

In some cases, the air conditioning unit will continue to run. If this occurs, you need to get to the bottom of why it is happening so it can be fixed.

While a continuously running air conditioner is no dire situation, it can cost you a lot of money over time. 

The good news is, even if your AC is exhibiting an issue, it doesn’t automatically mean that you need to replace the unit. However, it does indicate that it should be serviced sooner rather than later. 

In the sections below, we will cover in detail all of the reasons why your AC is running continuously.

1. Dirty Unit

If your air conditioner has been in use for even one season, you should take the time to thoroughly clean it.

Using an unclean unit is not only inefficient, but it is also a good way to cause damage that could be irreparable.

It is often easily overlooked as summer fades into fall, but your air conditioning unit must receive the proper maintenance to ensure it is properly functioning.

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It is recommended that your unit be cleaned thoroughly each year. (Source: Big Mountain Air)

Can I Clean the Unit by Myself?

Cleaning an air conditioning unit is a job that should be left to the pros. Sure, you can vacuum the unit and make sure it looks good on the outside.

But a professional should give the unit a once over to make sure all mechanical components are in working order.

2. Improper Temperature

Another reason your air conditioner may seem to be working overtime is if you have the temperature set too low in the unit.

If the air conditioner is continually trying to achieve an extremely low temperature, it may not ever turn off. 

On a hot day, you may be tempted to run your air conditioner at full force, but this is likely going to be ineffective.

It’s generally not a good idea to run your unit at a temperature at an extremely low temperature for extended periods because you run the risk of your unit freezing.

(Source: Advance Air)

3. Mechanical Issues

Unfortunately, you may have mechanical issues with your air conditioning unit that are causing it not to turn off at the proper time.

If a mechanical problem is to blame, you will likely need to have it repaired or replaced.

If your air conditioner has mechanical issues, you will likely begin to hear strange noises, followed by increasing energy costs.

When mechanical problems start, the unit must work overtime to complete the same job.

(Source: Rays HVAC)

4. Age

Although we wish it were true, air conditioning units will not last forever. If your unit is continuously running and you have had it for a long time, there is a good chance you will need to replace the unit because there is no repair for an aging unit.

On average, an air conditioning unit lasts between 10 and 12 years. Modern units will likely last a bit longer, but there is no guarantee.

With proper maintenance, you may be able to extend the life of your air conditioner.

(Source: Four Seasons Heating and Cooling)

5. Size of Unit

Often, a unit will run without stopping if it is the improper size for the area you are trying to cool. If the unit is too small, it will run constantly to make sure the proper temperature is reached and maintained.

When installing an air conditioning unit, it is crucial to take the size of the home as well as the climate zone into account. (Source: HVAC Direct)

If your air conditioning unit seems to be running non-stop, any of the above items may be the cause. 

Unless you are a trained HVAC technician, it is wise to seek the advice of a professional. 

How to Determine the Problem with Your AC

The most efficient way to determine what is wrong with your air conditioning unit is to call a professional.

After asking historical questions about the life of your air conditioning unit, they will likely do a diagnostic assessment and then clean the unit.

If you understand how air conditioning units work, you may be able to self-diagnose the problem. However, you may need help in repairing any problems that you discover.

Related: Why Humidity Goes Up When AC Is On?

What is Involved in a Diagnostic Test?

Most HVAC technicians will perform a diagnostic test on the air conditioning unit to ensure there is nothing mechanical or electrical going on within the machine. Typically, this assessment includes:

  • Testing the thermostat.
  • Visual external and internal inspection.
  • An analysis of the electrical components.

Some technicians may include more steps in the diagnostic process, but these are the most common. Once a diagnostic assessment has been completed, the technician will likely know the source of the problem. 

(Sources: Stack Heating and Air Conditioning, Heating and Refrigeration News)

How do Professionals Clean an AC for Maintenance?

One of the most common causes of air conditioner malfunctions is dirt and grime. If a technician determines the unit is running all the time because of dirt build-up, they will likely perform an intense cleaning of the unit.

The cleaning of an air conditioning unit can take quite a bit of time and needs to be performed correctly to ensure damage does not occur.

Typically, when cleaning an air conditioning unit, there are a few things that must be done:

  • Cleaning the coils both inside and outside
  • Clearing the lines of condensation
  • Calibrating the thermostat
  • Testing the thermostat
  • Cleaning the Coils

The first thing the technician will do is clean the coils both inside and outside. Over time, dirt can build up between the coils, which can impact the amount of airflow that moves through the unit.

If this dirt is not cleaned out periodically, it can cause damage to the unit. (Source: Carrier).

1. Clearing Lines

It is common for condensation lines to become clogged over time. When a clog occurs, it can inhibit the performance of the machine can make the unit run beyond the cooling point. 

Clogged lines can cause an increase in humidity as well. (Source: Thermacon)

When water gets stuck in the lines, it can also cause algae to begin growing. Not only is this bad for the air conditioning unit, but it can also cause an odor throughout your home when the unit is running. While this is not dangerous, it can be offputting.

2. Calibrating the Thermostat

Sometimes the thermostat is not calibrated with the actual air conditioning unit. When this happens, it is difficult for the air conditioning unit to keep up with the temperature in the house.

Because of this, the air conditioning unit may be forced to run beyond the set temperature. (Source: The Climate Tech)

3. Electrical Tests

One of the most important assessments a technician will complete is an electrical assessment.

When an air conditioner is running beyond the cooling point, it is important to rule out an electrical malfunction.

If the air conditioning unit has an electrical malfunction, not only will it work improperly, but it can also be a fire hazard. 

(Source: Energy.gov)

What Happens When Maintenance Does Not Work?

If you have called in professionals and maintenance does not work to resolve the issue of a continuously running air conditioning unit, it may be time to invest in a new air conditioning unit.

Not only will it provide a more efficient method of cooling, but it will also be cost-effective and safe.

How Much Does a Continuously Running AC Cost?

If your air conditioning unit is constantly running, you need to plan for the extra energy cost. Depending on the size of the unit, the cost will be between $0.06 and $.88 per hour. 

Because of this, you can plan to spend several hundreds of dollars each month in added cooling expenses. 

(Source: Learn Metrics)

Final Thoughts

The moment you notice your air conditioner is running non-stop, you need to enlist the help of a licensed technician.

Now you know the main reasons why AC’s run non-stop, and you have an idea of what to expect when you enlist the help of an HVAC technician.

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