How low can you set your AC before it freezes?

Author: Dr. Otto Gulgowski MD  |  Last update: Tuesday, December 30, 2025

Don't lower the thermostat below 72°F The higher altitude creates a different situation for an air conditioner so that it's easier for the evaporator coil to freeze over. At sea level, it's unlikely for an AC to suffer coil-freeze just because of a low thermostat setting.

How low can AC go without freezing?

Most air conditioners allow you to set a temperature at 60 degrees Fahrenheit or higher. If the temperature outside is below that, it isn't advisable to turn the air conditioner on as its coils may freeze and it may become damaged over time.

Will AC freeze up if set too low?

There is a point where your set point is too low and the system will freeze. This point is different in different systems and is also influenced by things like airflow and humidity. Once operating suction pressure drops below a saturation temp of 32 degrees F, you are going to start freezing up.

How cold does it have to be for your AC to freeze?

The temperature will need to go below -50 degrees for Freon to freeze. If the temperature outside during the winter is higher than that, you can expect the refrigerant to maintain its shape.

What is the lowest I can set my AC?

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.

8 Reasons Why Your AC is Freezing Up

How low is too low for an 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 lowest I can set my thermostat?

What's The Lowest Temperature I Can Set My Thermostat in Winter? Do you just love the cold so much you'd rather not run any heat in winter? The winter thermostat setting should at minimum be between 50-55 degrees to keep your appliances and pipes from freezing.

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 68 too low to set your AC?

During a heatwave, we recommend that you don't lower the AC's setting below 68°F. This is already quite chilly for most people, and many would consider it too cold. An air conditioner set this low risk of its coil freezing—and that's bad news because it indicates that the air conditioner is overworked.

Can you run AC below freezing?

Air conditioners can't tolerate temperatures below 60 degrees Fahrenheit. In extreme cold, the AC's compressor can get overworked as it struggles to function. At best, it will need significant repairs; at worst it may completely fail.

Is 67 too low for AC?

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.

Why won't my AC go below 73?

Dirty air filter: A dirty air filter can restrict airflow, which can make it harder for your AC unit to cool your home. If your air filter is dirty, it's recommended to replace it every 1-3 months. Low refrigerant: Refrigerant is a liquid that helps your AC unit transfer heat from inside your home to the outside.

Will my AC freeze at 68?

Using Your AC When It's Too Cold Outside

Lastly, if the temperature outside is below 60 degrees, and your AC's temperature is set below 68 degrees, this can cause the evaporator coils to freeze as there is not enough warm air in the house for the AC to sufficiently cool.

What is the coldest an air conditioner can go?

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.

Can running the AC too low cause it to freeze?

Performance issues: The goal when cranking up the AC is to cool your house more effectively, but an overworked air conditioner can freeze up if you set the temperature too low.

What happens if you set AC too cold?

You need your air conditioner to keep your home comfortable during the hottest months, but when the temperature is at its peak, you need to be careful. If you set the thermostat too low, it strains the AC. This leads to air conditioning malfunctions and costly repairs.

What's the lowest you should set your AC?

In short, the 20-degree rule of air conditioning states that you should always keep your AC unit at no more than 20 degrees lower than the outside temperature. It means that, if the outdoor conditions are at 95 degrees, you should set your thermostat at no less than 75 degrees.

Does keeping the AC at 72 save money?

Best AC Temperature Settings While You Are Home

As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.

Why is my AC set to 72 but reads 78?

Clean the Thermostat

Sometimes, when the room temperature doesn't match the thermostat setting, the problem could be dirt buildup on its interior parts. A dirt coating around the inner components may create excess heat and cause the thermostat to give the wrong readings.

Will AC freeze if it runs all day?

The constant running of your AC unit will reduce pressure in the evaporator, or cooling coil until it freezes over, according to Cool Today. This is why in some cases, this constant running can be dangerous. The freezing of the coil can cause liquid refrigerant to flood back into the unit's compressor and damage it.

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.

What temp will freeze AC?

Air conditioners are graduated to run within an ideal set of temperature thresholds. If you are operating your AC when the outdoor air is below 60 degrees, then the air pressure inside your unit will fall, and this can cause your Central Air Conditioner to freeze up.

What temperature to keep a house during a freeze?

Set your thermostat at a minimum of 55 degrees, especially when you are gone for the day or away for a long time. 68 degrees is ideal for when you are home. Let indoor faucets drip, but do not run a heavy stream of water (remember, it only takes a small drip).

What should I set my thermostat to when it's below freezing?

Preparing your home for winter can bring feelings of stress and an urgency to be prepared. But no matter how prepared your home is, you will still need to make a decision about the temperature at which to set your thermostat. The ideal thermostat temperature in the winter is 68 degrees Fahrenheit when you're at home.

Is 65 too cold for a house?

The World Health Organization recommends keeping indoor temperatures between 64 and 75 degrees Fahrenheit for healthy people. The minimum temperature should be kept above 68 degrees Fahrenheit to protect the very young, the elderly, or people with health problems. Watch out for signs of hypothermia.

Previous article
Is there a totally free plant care app?
Next article
How to disinfect a house after being sick?