HomeBLOGAir ConditionersWhy Won't My Air Conditioner Turn Off?

Why Won’t My Air Conditioner Turn Off?

If the air conditioner won’t turn off, it’s likely due to one of several common problems. A faulty fan, a problem with the thermostat, lack of maintenance, an inefficient condenser, extreme weather conditions, inappropriate air conditioner, or an electrical issue can cause the A/C to stay on even if switched off. 

When I want to cool down after a humid day outside, I can turn the air conditioner to stay comfortable indoors. When the cool afternoon sets in, I turn off your air conditioner and head out to get some fresh air. Unfortunately, my A/C decided to have a mind of its own decision to put out the ‘off’ option.

Of course, the wheels are turning in my mind, and I anticipate a skyrocketing electricity bill–and an uncomfortable environment to bear with. So, what does an average Joe do in this case?

Why Is My Air Conditioner Not Turning Off?

There are a few common reasons why an air conditioner might not turn off.

Malfunctioning fan 

The fan switch turns on or off according to the thermostat. It can also work independently using the fan limit switch by overriding the thermostat’s control on the unit. It’s best to check whether the fan switch is manual or automatic.

Damaged thermostat

The thermostat is the most crucial part of an AC unit responsible for regulating temperature. But it’s not immune to wear and tear.

Over time, a cooling system can become less accurate or experience damage that disrupts the flow of the HVAC equipment. A damaged thermostat could be turned to at a low setting, causing the unit to run longer than it needs to.

The air conditioner is the wrong size.  

When an AC unit is not large enough to cool the space, it will work on overdrive to reach the desired temperature. This overcompensation is destructive for its parts and could lead to costly repairs.

Extreme heat 

Even a well-rated air conditioner can struggle to keep up when the temperature reaches triple digits. If you’ve inspected your filters and it seems like everything else is usually working, there’s no cause for panic.

However, if the vents are continuously running with no relief from humidity, it’s best to wait until late afternoon or when the environment is cooler. If the problem persists, it’s time to call a professional HVAC to evaluate your unit.

Clogged filters 

Dirty filters could also be why an AC unit won’t shut off. A clogged air filter makes it harder for the unit to cool down and causes the unit to run on overdrive. Cooling cycles could take longer to complete, leading to higher electricity bills. Depending on the manufacturer, most air filters need to be replaced every 30 to 90 days.

Inefficient condenser and evaporator coils 

The condenser and evaporator coils are responsible for taking out moisture and cooling ambient air. Unfortunately, these coils accumulate dirt and debris from the surrounding air over time, causing it to clog up and prevent air from entering or going out of the unit.

Faulty electric wires 

If the air conditioner short circuits, the unit’s parts will likely not communicate as they should. There’s a good chance the thermostat may not respond when the AC is turned off. When there’s a short circuit, it’s important to ask a professional to evaluate the unit’s problems.

What Should I Do When My Air Conditioner Doesn’t Turn Off?

What Should I Do When My Air Conditioner Doesn't Turn Off?

If your air conditioner is not turning off, there are a few things you can do:

  • Check to see if the thermostat is set to “off.” If it’s not, change it to “off.”
  • Ensure no debris blocking the air conditioning part, fan, or thermostat. Clean the areas where debris has settled.
  • Turn the fan setting from ‘on’ to ‘auto’ mode. It keeps the fan from running throughout a cooling cycle.
  • If used for more than 90 days, replace air filters or have noticeable debris forming on the surface.
  • If there is a power outage, wait for power to be restored before trying to turn the air conditioner off.
  • Wipe debris forming on the evaporator and condenser coils.
  • Ask an HVAC professional to check whether the AC unit is appropriate for the size of the room. Larger homes require units with higher BTU (British Thermal Units) to maintain a comfortable temperature.
  • Clean the debris from the evaporator and condenser coils using a mixture of warm water with a household cleaning agent. Let this sit for about 10 minutes before wiping the dirt off the coils using a soft cloth.
  • Have an HVAC technician service the AC unit before the summer season or mid-year.
  • If none of these solutions work, call a technician to troubleshoot the problem. There may be other factors keeping the AC unit from functioning normally. An HVAC expert could also help provide the appropriate solutions to maintain a comfortable environment for homes and offices.

People Also Ask

Why does my air conditioner fan keep running after I turn it off?

The air conditioner fan may be at fault for causing the fan to run throughout the cooling cycle. It could be something as simple as a dirty fan blade preventing the unit from shutting off. Check the fan setting and see if it’s under ‘auto’ mode instead of ‘on’ to allow cooling.

There could also be other internal issues within the unit, such as a malfunctioning thermostat. Other components such as condenser coils and evaporating coils could be at fault.

It’s best to call a professional when all interventions have been exhausted. The air conditioner may require further evaluation for maintenance or repairs.

Why is my thermostat not turning off?

The thermostat is not turning off because of damaged or faulty wiring, a bad connection, or not getting power. Calling an HVAC technician will be able to assess the condition and check if other factors are hindering the thermostat from functioning.


Although air conditioners are standard in summer, there are still many instances where ACs may not function efficiently because of faulty wiring, dirty fan blades, thermostat issues, etc.

If the air conditioner isn’t turning off, it’s important to troubleshoot the issue and find a permanent solution. Again, ask a professional HVAC technician to maintain the unit’s integrity.

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