Why does my AC run for 15 minutes then shut off?

Author: Stefan Mann MD  |  Last update: Saturday, April 19, 2025

Take a look at your air filter. If it looks dirty, have it replaced. A refrigerant leak can lower the pressure in your air conditioner, which [similar to a dirty air filter] will cause the evaporator coils to freeze and the AC unit to turn on and off repeatedly.

Why does my AC work for 15 minutes then stops?

Electrical problems are a common cause of short cycling. This may indicate that there is an issue with the electrical supply line or the capacitor could be broken or failing. This can be caused by the thermostat, electrical connections in the system, or the circuit boards.

Why does my air conditioner run for 10 minutes then shut off?

If your air conditioner is turning on and off quickly, it may be short cycling. Short cycling is a serious problem that will almost always lead to the AC condenser outside your house wearing out more quickly if you don't repair the underlying problem. The compressor motor is always under lots of strain as it starts up.

Why does my AC run for a little then stops?

Several reasons could cause your air conditioner to keep shutting off, such as a dirty filter, low refrigerant, or a malfunctioning thermostat. To fix it, try cleaning or replacing the filter, ensuring proper refrigerant levels, and checking for thermostat issues.

Why does my AC turn on then off after a few minutes?

If your AC unit is turning on and then off right away, there are several possible causes. These include thermostat problems, refrigerant leaks, oversized AC units, and dirty air filters. With the exception of a dirty air filter, most of these issues should be addressed by a qualified HVAC technician.

9 Reasons Why Your Air Conditioner Starts Then Stops Quickly

How to tell if a thermostat is bad?

A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.

How do I stop my AC from short cycling?

How To Stop and Prevent Short-Cycling
  1. Check your air filter. Believe it or not, a clogged air filter can cause a wide variety of air conditioning issues. ...
  2. Check your thermostat placement. ...
  3. Check your air conditioner's refrigerant levels. ...
  4. Replace the low-pressure control switch. ...
  5. Check the compressor.

How to know if AC is short cycling?

When your AC turns on, it will usually need to run for anywhere from 10 to 20 minutes to cool your home completely. If the AC turns on and quickly shuts off again within a couple of minutes, there might be a major issue causing your unit to short cycle.

How to tell if AC refrigerant is low?

Here are some of the symptoms of an air conditioner with low refrigerant:
  1. Takes Your AC a Long Time to Cool Off. ...
  2. Indoor Air Not Blowing Cool Enough. ...
  3. Frost or Ice on Copper Lines. ...
  4. Water Pooling Around the Furnace. ...
  5. Listen for a Hissing or Bubbling Noise. ...
  6. Short Cycling. ...
  7. Electric Bills Higher.

Why does my AC run for 10 minutes then trip the breaker?

Typically, your AC breaker trips when there's a short circuit, the AC is overworking or a part is bad or malfunctioning. If you continue to run your AC, you could permanently damage the air conditioner. Get a professional AC repair tech out as soon as you can.

How long should an air conditioner run before it shuts off?

When things are working right, your central air conditioner should run for 15 to 20 minutes and then turn off for a few minutes. It will do this two or three times every hour. It may run longer when it's sweltering outside.

What does short cycling mean?

In the heating, ventilation, and air conditioning (HVAC) business, short cycling is a phrase used to describe when a heater or air conditioner cycles on and off too frequently. It signifies a problem in your heating system's proper functioning and efficiency, in which it is not completing its heating processes.

How do I fix my air conditioner that keeps turning off?

Clean the condenser coils: Dirty condenser coils can cause the AC unit to overheat and turn off by itself. Use a soft brush or vacuum cleaner to clean the coils regularly. Call a professional: If the issue persists, it may be time to call a professional HVAC technician to diagnose and fix the problem.

How to clean air conditioner condenser coils?

These are the steps our technicians take to make your AC's outdoor coil clean and sparkly:
  1. Turn off power to the unit. ...
  2. Check the refrigerant pressure. ...
  3. Remove the outer casing. ...
  4. Rinse the coil down with water. ...
  5. Spray the coil with cleaning chemicals. ...
  6. Re-rinse the coil with water.

How to reset an air conditioner?

Reset the AC Using the Isolation Switch

The isolation switch looks like an ordinary light switch with a knob. Once you locate it, turn the knob to the off position and leave it for at least 30 minutes up to an hour. This will allow the electrically operated components in the AC to reset.

How often should I add refrigerant to my AC?

Most systems need Freon replacement anywhere from once every two to five years from a professional HVAC Contractor. The most significant exception to this rule is when there is a leak in the air conditioning system, which decreases the amount of refrigerant in an AC unit over time.

How much does it cost to fix low refrigerant in AC?

If you simply need a top off of refrigerant, you can expect to pay anywhere from $160-$375. If you need a repair for the leak itself, you can anticipate a higher bill. For refrigerant leak detection and air conditioning repair you may pay anywhere from $550 to $1,600.

How do I know if my air conditioner needs Freon?

You might feel warm air flowing through the vents, or you might notice that your AC is weaker than it used to be. If air flow seems fine, but the air coming up isn't cool, then you likely have a refrigerant problem.

Why does my AC turn on for a minute then stops?

Modern air conditioners are equipped with safety devices to shut them down when overheating happens. Thermostat problems—The wiring may have been damaged on your thermostat or it could be as simple as incorrect settings. A poorly chosen thermostat location can also cause an AC unit to short cycle.

Can you fix a short cycling air conditioner?

Our technicians will find and fix refrigerant leaks and add refrigerant so your AC unit has the proper levels to operate efficiently. Ensure Proper Sizing: Persistent short cycling can be due to an improperly sized air conditioner. Unfortunately, the only solution in this situation is to replace your cooling system.

How to check refrigerant level in AC?

Steps for Checking Refrigerant Levels
  1. Turn Off the AC and Remove the Cover. Turn off the AC unit and remove the cover to access the refrigerant level gauge or gauges.
  2. Locate and Remove the Access Panel. ...
  3. Attach Refrigerant Pressure Gauges. ...
  4. Interpret Pressure Levels. ...
  5. Add Refrigerant (if Necessary)

How long should AC run before cycling off?

Each cycle's length depends on the thermostat settings. Once the AC completes a cycle of about 15 and 20 minutes, it should remain off for 7 to 10 minutes. This helps it cool off before starting another cycle. The stops happen 2 to three times per hour.

How much does it cost to fix a short cycling AC unit?

Central AC Short Cycling

Homeowners spend between $75 and $600 to deal with short cycling issues in their central AC systems.

Can a thermostat cause AC to short cycle?

Several issues can cause short cycling, such as an oversized HVAC system, a clogged air filter, or a malfunctioning thermostat. Low refrigerant levels or a blocked evaporator coil can also force the system to shut down prematurely.

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