Why does my AC only run for a few minutes?

Author: Prof. Darryl Boehm  |  Last update: Friday, October 24, 2025

AC compressor short cycling is often caused by an oversized unit, clogged air filters, refrigerant leaks, or faulty electrical connections, leading to inefficiency, increased wear and tear, and reduced lifespan.

Why does my AC run for a few minutes then stops?

Typically, short cycling can come from an incorrect unit size or programmable thermostat problems. However, it could also be caused by neglected routine maintenance or something that might require a simple repair.

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.

What is the 3 minute rule for air conditioners?

Depending on the system, an optimal time of 3 minutes is required before switching the system on. If the system is turned on without waiting for at least 3 minutes, the system can start with a pressure load. This pressure load prevents the system from cooling properly, which could affect the system in the long run.

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.

Why my AC stops cooling after some time?

How to tell if AC is short cycling?

The system will turn off prematurely and then quickly turn back on in an attempt to reach the set temperature. The thermostat will incorrectly tell the unit that the set temperature was reached or vice versa. A miscalibrated thermostat puts lots of strain on the HVAC system and can be a difficult problem to notice.

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.

Why does my AC only stay off for 5 minutes?

A miscalibrated, malfunctioning, or poorly placed thermostat can cause your AC to short cycle, as it may not correctly register the temperature. If your thermostat is too close to a supply vent, the cold air coming out of the vent will quickly make it think your home is cooler than it is.

How long should your AC run before shutting 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.

How do you set a thermostat to prevent short cycling?

You can adjust the CPH's (cycles per hour) in the thermostat installation settings. This will increase run times and will result in a wider temp swing with increased humidity removal.

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 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.

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.

Why does AC shut off after a few minutes?

If something blocks the flow of air, your AC needs to go into overdrive to make up for it, which could result in it overheating. And when your AC overheats, it shuts off to give the system a chance to cool down. Once cool, it turns back on again, and the vicious cycle of short cycling continues.

Why does my compressor stop after a few minutes?

Blocked airflow, refrigerant issues, and faulty electrical components are common causes that can lead to your AC compressor shutting off after a short period. Blocked airflow can be caused by clogged air filters or closed air vents, leading to the compressor overheating and shutting off.

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

Your Air Conditioner May Be Short Cycling

When an air conditioner short cycles, it turns off before reaching the desired temperature. It may not be long before the thermostat recognizes this and instructs the AC to run again. But since there's a problem, the air conditioner will continue to short cycle.

How often should AC kick on and off?

What Is Frequent Cycling? AC frequent cycling, also commonly referred to as short cycling, occurs when the AC cycles on and off too much. An air conditioner operating with good efficiency will only cycle on and off about two to three times an hour. Air conditioners can generally cool a space in about 15 to 20 minutes.

Is it OK if my AC runs constantly?

The warmer the temperature is outside, the longer your AC will run to get your home to your desired temperature. Longer runs times are good in these conditions: it means your air conditioner is working the way it should. But even then, you should still be able to hear your air conditioner turn off and on as needed.

Why does my AC kick on then shut off?

Dirty or Frozen Coils

If the condenser coil is dirty, your AC can't complete the cooling process. It can cause the unit to malfunction and shut down whenever you turn it on. To avoid this, clean the condenser coil regularly. You can use a coil brush to clear debris and a fin comb to realign the coil fins.

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.

Can a thermostat cause short cycling?

Your thermostat could also cause the HVAC system to cycle on and off rapidly, a process known as short cycling.

How much does it cost to fix a clogged condensate drain line?

Flush Condensate Drain Line

The repair cost to have the drain line flushed runs between $75 to $250.

What are the symptoms of HVAC short cycling?

Common symptoms include rooms that don't reach the desired temperature, uneven heating or cooling, and an HVAC unit that starts and stops constantly. While short cycling might initially seem like a simple inconvenience, it can lead to more significant problems if not addressed promptly.

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.

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