Why does my AC never turn off?

Author: Weldon Erdman  |  Last update: Wednesday, June 25, 2025

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.

Is it normal for AC to never shut 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 do I fix my AC that won't turn off?

How to Fix an Air Conditioner That Won't Turn Off
  1. Change Thermostat Settings. Turn up the temperature so the thermostat is set a few degrees higher than the current room temperature. ...
  2. Change the Fan Setting. ...
  3. Facilitate Good Air Movement. ...
  4. Clean Blower Fan.

Why is my AC running constantly?

The Short Answer Is: When your air conditioning system keeps running and never seems to shut off, the problem could be linked to a number of malfunctioning components – frozen evaporator coils, a clogged air filter, a bad electrical relay switch that needs to be replaced, the fan blowing constantly, dirty condenser ...

Why is my AC not switching off with the remote?

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.

7 Main Reasons Why Your AC Won’t Turn Off

Why isn't my AC kicking 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.

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.

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.

Why won't my AC turn off when it reaches the set temperature?

If the indoor unit continues to operate after the temperature is reached and the temperature does not continue to drop, you more than likely have the fan switch on the thermostat set to the "on" position instead of the "auto" position.

Why is my AC staying on too long?

Dirty, clogged or overly restrictive filters may be the cause of many heating-and-cooling problems, including a constantly running AC system. What you can do: Turn your air conditioner off. Remove and inspect your HVAC filter.

How to tell if your 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 stop my air conditioner from turning off?

Change the air filters: Dirty air filters can cause the AC unit to overheat and turn off by itself. Changing the air filters regularly can help prevent this issue. Check the thermostat: Make sure the thermostat is calibrated correctly and set up properly for your home's climate conditions.

How long should an AC run to drop 1 degree?

On average, an air conditioner running in good condition should take about 15-20 minutes to drop the temperature by 1 degree in a standard-sized room. However, factors like outside temperature, unit size, and insulation quality can affect this timing.

How often should I change my AC filter?

How Often Do I Need to Change Out My Air Filter? Generally, most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days, or 3 months. That can change based on where your home is located (ex. dusty, dry climates), if you have any pets, and the age of your system and equipment.

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 does my AC keep running after it has reached the set temperature?

Common Causes of an AC Running Constantly

If your AC cooling cycles last more than 30 minutes or run all day, you likely have one of the following common AC problems: Thermostat fault. Dirty or clogged air filter. Low refrigerant.

Why is my AC thermostat set at 74 but reads 78?

If the temperature is set to 74°F but the thermometer shows 78°F, you will have to recalibrate the thermostat to account for this 4-degree deviation. Even with older AC units or furnaces, you might have to recalibrate your thermostat from time to time.

How long is too long for an AC unit to run?

Your AC unit should run its cycles for about 15 to 20 minutes, no more than a couple of times within an hour. If your AC is running for long cycles, it could also indicate a problem. Any AC system failure left unsolved could mean a costly repair and a hefty electricity bill.

How to reset a thermostat?

Most modern thermostats will have a clearly marked reset button inside the panel. It's usually small and recessed, so you might need a pointed object like a paperclip to press it. For those wondering specifically how to reset air conditioner thermostat models, the process is generally the same.

What happens if air conditioner runs continuously?

The constant running will reduce pressure in the cooling coil until it freezes over, which is dangerous as it can cause liquid refrigerant to flood back to the compressor and damage it (the compressor is a very expensive part).

Is it normal for AC to run constantly in summer?

It's summertime, and you've noticed your AC never stops running. Should you be concerned? Here's the thing: It's normal for your AC to run continuously during hot summer months. You see, on extremely hot days—we're talkin' high 90s to 100s—your system needs to keep up with the incoming heat.

Do air conditioners need to rest?

Allowing your air conditioner to rest is an excellent way to extend its life and ensure it operates efficiently throughout the years. Air conditioners, like homeowners, require rest in order to recover and perform optimally.

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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