Why won't my AC stop running?

Author: Magdalen Crist  |  Last update: Wednesday, June 18, 2025

If your air conditioner will keep running no matter what repair you try, malfunctions or faulty components are to blame. You could have a dirty air filter, clogged condenser coils, frozen evaporator coils, a broken relay switch, or a bad thermostat, amongst other common air conditioner issues.

What does it mean when your AC doesn't stop running?

If your AC won't turn off, it could be due to thermostat malfunctions, electrical component issues, dirty or clogged components, or an incorrectly sized system, which can increase energy bills and reduce system efficiency.

How do I stop my air conditioner from running constantly?

What you can do:
  1. Turn your air conditioner off.
  2. Remove and inspect your HVAC filter. ...
  3. Ensure your filter isn't too restrictive and meets manufacturer recommendations.
  4. Clean/replace dirty or clogged filters as necessary.
  5. Install or reinstall new filter (ensure you install it to face the correct direction).

Why is my AC unit not shutting off?

Malfunctions affecting different system components can prevent the conditioner unit from shutting down as expected, such as a clogged air filter, a frozen evaporator coil, a faulty electrical relay switch, a dirty condenser coil, a constantly blowing fan, a bad thermostat, low refrigerant, and other HVAC system repair ...

Why is my AC not getting off?

Check the set temperatures on your thermostat – if the set temperature is lower than the current room temperature, the air conditioner cycle will not stop. Adjust the temperature up a few degrees higher than the current room temperature, which should trigger the thermostat to shut down the air conditioner.

7 Main Reasons Why Your AC Won’t Turn Off

What happens if AC never turns off?

If your air conditioner will keep running no matter what repair you try, malfunctions or faulty components are to blame. You could have a dirty air filter, clogged condenser coils, frozen evaporator coils, a broken relay switch, or a bad thermostat, amongst other common air conditioner issues.

How long can AC run continuously?

In general, wall and window air conditioning units with smaller capacities can typically run for up to eight hours at a time before they need to rest. Larger wall and window units have a longer running time of around 10 to 12 hours, depending on their cooling power.

How can I get my AC to turn off?

You can completely turn off the air conditioner by adjusting the thermostat. Look for a button that allows you to toggle between “heat,” “cool,” and “off.” Simply set the thermostat to the “off” position to stop the AC from running.

Why is my AC unit still running when the thermostat is off?

It is concerning when your AC won't stop running even when turned off and it could be an indicator that something is wrong within your system. An AC unit that is too old or too small for your home may run all day which can only be fixed with a complete replacement of your AC unit.

How do I know if my thermostat is bad?

7 Ways to Tell Your Thermostat Is Broken
  1. The Thermostat Has No Power. ...
  2. The AC or Furnace Won't Turn On. ...
  3. The Heater or AC Won't Turn Off. ...
  4. The Thermostat Reading Doesn't Match the Room Temperature. ...
  5. The Thermostat Doesn't Respond. ...
  6. The HVAC System Is Short Cycling. ...
  7. The Thermostat Forgets Programmed Settings.

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.

How do I know if my AC is running too much?

7 Signs You're Overworking Your Air Conditioner
  • Shocking Increases in Your Energy Bills. ...
  • Your Air Conditioner Struggles to Cool Your Home. ...
  • Your Home is Uncomfortably Humid. ...
  • You Are Wearing Out Your Thermostat Buttons. ...
  • Your House has Warm and Cool Spots. ...
  • You Hear Strange Noises. ...
  • Your HVAC System Leaks.

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.

Why is my thermostat not turning off?

It could be the wrong thermostat setting is being used, a clogged air filter or your thermostat itself is no longer working properly. When you have a heating system not shutting off, this issue makes it difficult to maintain the desired temperature inside the home.

Can a bad thermostat cause AC to run constantly?

If the AC unit or furnace constantly runs and doesn't turn off when the desired temperature is reached, the wiring within the thermostat may be failing. It can also be a sign of miscalibration, which causes the thermostat to send the incorrect signals to the air conditioner, furnace, or heat pump.

Why won't my blower fan turn off?

If your furnace fan won't turn off, you most likely have one of these 3 problems: Your furnace fan limit switch is set to “manual override” The fan limit switch is faulty and needs to be replaced. There's a problem in your thermostat wiring.

Why is my AC running without stopping?

Like we mentioned above, refrigerant is what absorbs the heat from your home's air. Not enough refrigerant in the AC system will stop it from absorbing as much heat from the air, prolonging the cooling process and causing your AC to run continuously.

How do I reset the thermostat on my AC?

Switch the thermostat to the off position. Locate the breaker that powers your HVAC system and turn it off. Wait 30 seconds and turn the breaker back on. Turn your thermostat back on and confirm it has reset properly.

Why is my AC not shutting off?

If your air conditioning system won't turn off, there are most likely malfunctioning mechanisms, such as a faulty thermostat or fan limit switch, frozen evaporator coils, electrical issues, or incorrect thermostat or fan speed settings.

Why is my AC constantly running?

Your Filter Needs Changing

Air can't flow freely into the system, so the unit has to work harder to keep your home cool. So, if you notice your AC is running constantly, check the filter first to see if it's dirty and needs to be replaced.

How long should it take for AC to turn off?

As suggested by experts, the cooling cycle of an AC is supposed to last for at least 15 minutes. In this duration, the compressor and air handler distribute the desired cooling inside the room. But when this normal cycle is disturbed and reduced to 10 minutes, we can call this a short cycle that needs prompt repair.

Is it bad for AC to run nonstop?

Leaving your air conditioning unit running all day won't typically cause damage to the unit itself, but it can strain the system and result in costly energy bills. Running your air conditioner non-stop for extended periods without regular maintenance leads to wear and tear on the unit.

What happens if an AC compressor runs continuously?

The longer your unit runs, the more power it will pull and the higher your electric bill will be. Your air conditioning unit has an expected operating life. Once that operating life is reached, it will become defective and inoperational.

What happens if the AC is left on too long?

Allowing your air conditioner to chug away all day and night may lead to these outcomes: High energy bills: The time an appliance runs and the amount of energy it consumes are directly proportional. So the longer your AC operates, the more energy it guzzles, leading to sky-high utility bills at the end of the month.

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