How low can you run central AC?

Author: Dr. Tod Green  |  Last update: Monday, October 20, 2025

But you shouldn't run your AC if the temperature is below 60°F.

How low is too low for central air?

The lowest outside temperature at which to run your AC is typically around 60-65 degrees Fahrenheit. At temperatures below this range, your air conditioner might not operate efficiently, causing increased energy consumption and potential strain on the system.

Is it OK to set an AC below 70?

What Temperature is Too Cold for a House AC? Most experts maintain that running your AC below 70 degrees can cause issues with your unit, including the risk of freezing the evaporator coil.

What's the lowest you can set your AC?

Unlike low temp refrigeration systems, like your freezer, your AC unit is not designed to take your space into freezing temperatures – not even close! An AC unit is happiest creating space temperatures no lower than 68 degrees fahrenheit.

How low can I run my AC unit?

I wouldn't worry about running it even down to 50/55°. You'll only run into a problem if you're trying to cool the house too low, say 65°, in conjunction with a lower outdoor ambient. It's easier to start freezing up the coil that way.

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What happens if you run your AC too low?

If you set the thermostat too low, it strains the AC. This leads to air conditioning malfunctions and costly repairs.

Is it bad to run AC below 60 degrees?

In most cases, especially in residential applications, you should not run your air conditioner when outdoor temperatures are below 60 degrees. The air conditioner does function, but you are going to burn out the compressor fairly quickly.

How cool should my house be if it's 100 outside?

For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.

How low can I set my AC at night?

According to the Cleveland Clinic, the recommended thermostat setting for nighttime is between 60°F and 67°F. 3 Setting your AC within this range can help maintain a comfortable sleeping environment.

What is the lowest point of AC?

The minimum point of AC curve falls towards right of AVC curve because AC continue to fall even after AVC starts rising because AFC falls.

Is 68 too low to set AC?

In order to prevent your AC from overworking and breaking down, it's important to keep the temperature setting on your thermostat at a reasonable level. During a heatwave, we recommend that you don't lower the AC's setting below 68°F.

What is the 20 degree rule for air conditioners?

Simply put, it means you should never set your thermostat for a temperature more than 20 degrees cooler than the outside air. Why not? Most air conditioning systems can only handle a 20-degree difference between the outside and inside air temperatures.

How low to set AC in summer?

The recommended rule of thumb for summertime is to set the temperature to 78 degrees Fahrenheit when you're home and higher when you're away. In general, set it to 82 degrees Fahrenheit when you're asleep and 85 degrees Fahrenheit when you're away.

Is 72 too cold for AC in summer?

To maintain a comfortable indoor environment during the summer, the American Society of Heating, Refrigerating & Air Conditioning Engineers recommends a range of 73 to 79 degrees Fahrenheit. On scorching hot days, you may want to adjust your thermostat toward the higher end of that range.

How low can you set your AC before it freezes in summer?

This sounds unbelievable, but it does happen, especially in higher altitudes. This is why many HVAC experts say you shouldn't lower your thermostat below 72 degrees during warm months or below 78 degrees in the hot months.

Is it bad to set AC below 70?

While you can set your air conditioning thermostat below 70 degrees, it is generally not recommended due to potential efficiency issues, higher energy costs, and increased wear and tear on your system.

What is the lowest an AC should be set at?

For example, HVAC specialists recommend setting your thermostat no lower than 20 degrees the outside temperature. Suppose the outdoor temperature in your area is a blistering 90 degrees Fahrenheit. It's probably best to keep your thermostat between 70 and 80 degrees Fahrenheit to prevent stress on your unit.

What happens if I set my AC too low?

In most cases, air conditioners only have one speed (though some have variable speed settings to improve energy efficiency). Lowering the temperature too much causes your air conditioner to operate longer, causing more wear and tear on it as well as higher utility bills.

How low can central AC go?

Your AC has limits, no matter its age, how well it was installed, its manufacturer, etc. As a rule of thumb, when it's 95 out, your AC can cool your house to approximately 70-80. Your air conditioner will be able to cool to about 15-25 degrees from the outside temperature.

How cool should my house be if it's 110 outside in summer?

The California Energy Commission recommends that homeowners set their thermostat to 78 degrees when they're home and 85 degrees when they're away from home during the summer.

How low can I set my AC on a 100 degree day?

For the most efficient performance, set the thermostat 20 degrees lower than the temperature outside. On a 100℉ day, set it to 78℉ to 80℉ to manage utility costs. If there's a lack of airflow, the filter may need to be changed or AC vents cleaned.

How long should it take to cool a house from 80 to 72?

Cooling a house from 80 to 72 degrees is a common goal for many, especially during the peak of summer. On average, this process takes roughly two and a half to three and a half hours.

How low can I run my AC?

But you shouldn't run your AC if the temperature is below 60°F. Heat pumps: Modern heat pumps are effective at around 25 to 30°F. Ductless mini-splits: Avoid using the cooling function when temperatures fall below 60°F.

Is 67 too low for AC?

When the AC temperature is too low, between 60-67 degrees F (15-19 degrees C), the evaporator coil inside the unit can get excessively cold. If the humidity in the room is high, condensation can accumulate on the coil, which may lead to the formation of frost or ice.

What is the best temperature for AC on a low bill?

You can also reduce your energy costs significantly by raising the temperature while you are at work, away from home, or asleep. For the greatest savings, consider setting your thermostat to: About 78 degrees while you are at home. About 82 degrees while you are sleeping.

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