Why does my AC kick on then shut off?

Author: Prof. Darrion Waters  |  Last update: Monday, August 18, 2025

If your air conditioner turns on and off right away then your thermostat may be broken. The thermostat could be reading the temperature of the home incorrectly, thereby communicating misinformation to your AC unit, causing it to turn on and off. Check your thermostat first.

Why does my AC come on and then shut off?

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.

Why does my AC run for 5 seconds then shut off?

There are various reasons for your portable AC compressor to turn OFF frequently including dirty filter, clogged condenser, leaking refrigerant or a faulty compressor. Timer or inadequately set or faulty thermostat could also lead to consistent turning ON and OFF of portable AC.

Why does my AC start blowing then stops?

Dirty or Frozen Coils

The condenser coil is where the refrigerant releases the heat absorbed from the air. 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.

Why does my air conditioner run for a minute then shut off?

Some common causes include: Overheating—This can often be caused by a buildup of dirt and grime on the evaporator and condenser coils or a refrigerant leak. Modern air conditioners are equipped with safety devices to shut them down when overheating happens.

9 Reasons Why Your Air Conditioner Starts Then Stops Quickly

How to fix AC short cycling?

Fortunately, there are plenty of ways you can put an end to your air conditioner's short-cycling issues:
  1. Check your air filter. ...
  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 low on refrigerant?

Warning Signs of Low Refrigerant in Your AC or Heat Pump
  1. Weak Airflow or Warm Air Blowing from Vents. ...
  2. Poor Cooling Performance. ...
  3. Constant Cycling On and Off. ...
  4. Ice Buildup on Refrigerant Lines or Evaporator Coil. ...
  5. Hissing or Bubbling Noises.

Why does my AC work for a little while 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 is my AC fan kicking on and off?

You may have a dirty air filter problem. When the air filter restricts airflow, the evaporator coil can become frozen, causing the unit to turn on and off. As a reminder, air filters should be replaced at least once a month. You may do this more often if you are constantly running your air in the summer.

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)

Should I turn off my AC if it's short cycling?

Should I turn my AC off if it is short cycling? No, this is not necessary unless the evaporator coils are frozen, in which case, turn off your air conditioner to let the coils thaw.

How to unclog an AC drain?

To unclog an AC drain line, turn off the power to the unit. Locate the drain line and use a wet/dry vacuum to suck out the clog. Flush the line with water using a garden hose or cup of water. Check and clean the drain pan under the indoor unit.

What happens if an AC condenser is dirty?

A dirty condenser coil can negatively impact the indoor air quality of your living or working space. When the coil is clogged, airflow becomes restricted, and the air passing through the system may pick up dirt, dust, and other contaminants present on the coil's surface.

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 my AC turn on and then turn right back off?

If your air conditioner turns on and off right away, this could also be due to your system having a refrigerant leak. When your system is running low on coolant, the compressor isn't able to operate properly, causing it to shut down. Always have a HVAC specialist handle a possible refrigerant leak in your AC unit.

Why does my AC stop working after 5 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.

How to tell if a relay is bad HVAC?

AC Fails To Start: An air conditioner that doesn't start at all is a clear sign of a relay issue. The relay may be unable to send the necessary signals to power up the system. Blower Motor Issues: Since the relay also controls the blower motor, any irregularities in airflow might be due to a faulty relay.

Why does AC kick on and off?

Your air conditioner may be short cycling because it is repeatedly starting up then overheating (and shutting down) due to a bad compressor, dirty filters, dirty coils, low refrigerant, or frozen coils. An overcharged system will cause liquid Freon to get into your compressor and cause it to malfunction.

Why is my AC fan starting and stopping?

Faulty wiring, loose connections, or electrical component failures within the AC unit can lead to intermittent power loss, causing the condenser fan to short-cycle. These electrical problems can pose serious risks, including potential damage to your system or even fire hazards.

What is the average lifespan of an air conditioner?

While every unit is different, and every homeowner has a different understanding of when their central air conditioner is broken beyond repair, it's fair to say that, with proper maintenance and care, you can expect a good 15 to 20 years of cooling from a new high efficiency air conditioning system.

What is the first thing to check when the AC stops working?

Check these issues when the unit won't kick on: Check the thermostat and adjust the settings if it isn't set to Cool and an appropriate temperature setting to call for cooling. Examine the house circuit breakers for the AC unit and reset any tripped breakers. Check the air filter and replace the filter if it's dirty.

Why does my AC run for 30 seconds then shut off?

Cause 1: Low refrigerant/Freon

Your AC compressor has a device called “low pressure control.” Basically, it can shut off the compressor when you're low on refrigerant. And if you're low on refrigerant, that means you also have a refrigerant leak that needs repairing.

How do I know if my AC needs recharging?

Take note of the strength of the air that blows out of your AC vents. If you notice weak or low airflow, this could likely mean you're running low on refrigerant. Be sure to rule out any other potential causes before recharging your refrigerant.

Can AC lose refrigerant without a leak?

Refrigerant is a working chemical that runs through your car's A/C system in either a gaseous or liquid form. Causes of refrigerant leaks in your vehicle include physical damage, wear and tear over time, and escaping refrigerant even without a leak.

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