It’s not challenging to adjust the temperature on your thermostat to keep you cool during Iowa summers. But, it can be confusing which thermostat fan setting you should use: on or automatic, otherwise known as auto. It’s a common question that many homeowners have. In most cases, auto is the best option, but there are instances where you may want to use the on setting or a combination of both called circulate.
There is no right or wrong answer, but by understanding the pros and cons of each setting, you can use them more efficiently for your home.
On vs. Auto
The on and auto settings both control the AC blower fan, which is located in the indoor part of your AC unit. The fan pulls warm air into your air conditioner to be cooled and then blows the cool air back into your home. When you select the auto setting, the fan turns on automatically when your system is cooling air. After your thermostat reaches the set temperature, the AC fan shuts off until the next cycle. The on position sets the fan to run continuously.
Benefits of Setting Your Thermostat to On
Choosing the on setting helps the air flow more evenly throughout your household and can eliminate hot or cold zones. In extreme heat, it’s beneficial to keep your thermostat set to on to help regulate the indoor temperature as well as to allow your AC unit to not work as hard. If you have a two-story home, this setting can help eliminate temperature differences between floors that you may face during the summertime.
You may also notice better indoor air quality when your fan is set to on. In this setting, the air continuously moves through the furnace filter, helping remove allergens and potential indoor pollutants.
In addition, running your AC system fan continuously can reduce wear on your motor because it’s not starting and stopping all day like it would if it were set to auto.
Thermostat Settings
While there are certainly advantages to keeping your thermostat set to on, there are disadvantages too. Since your AC fan is constantly running, it increases your energy costs. Unless a variable speed motor is installed, it can cost you as much as $50 more each month . How much your costs increase will depend on the age and efficiency of your system.
Another disadvantage of keeping the fan running is that your furnace filter can collect more dust in a shorter amount of time, which may require you to change it more frequently. A clogged furnace filter makes the blower motor work harder and uses more electricity.
The Advantages of Setting Your Fan to Auto
Setting your thermostat to auto will allow your system to be more energy-efficient since the fan only runs when the system cycles on, not continuously. Typically, the fan will turn on 30 to 60 seconds after a heating or cooling cycle starts and then turn off a minute after the cycle ends.
Another advantage is that you don’t need to replace your air filter as frequently since air isn’t constantly moving through the air filter. You can maintain a monthly or every-other-month changing schedule.
Disadvantages of Setting Fan to Auto
Keeping your fan set on auto causes it to have more starts and stops, which can wear out the fan more quickly. Over time that can lead to less efficient distribution of air inside the home and potential equipment repairs.
When using the auto setting, you may notice hot or cold spots in your home. And there’s the potential for decreased indoor air quality since the air isn’t constantly being circulated through the filter. When the fan isn’t running, the air may also feel humid or stuffy. If you are noticing high humidity levels in your home, try turning your fan to the on setting.
Fan Circulate
Some newer homes have smart thermostats equipped with a third fan option, circulate, which is a combination of on and auto. This setting runs the fan during the cycle and then again for a few minutes every hour. This is a great alternative if you want to have better air circulation but not the increased energy costs that come with the on setting.
Consider Adding a Variable-Speed Air Handler
Installing a variable-speed air handler can give you the comfort and air quality improvements that the on setting has with the energy-saving advantages of the auto function. A variable-speed motor isn’t restricted to specific settings; it can run at any speed within a set range. This allows it to choose the precise speed that’s most efficient for the given heating demand.
You rely on your AC unit to keep you and your family cool. If your home isn’t maintaining a comfortable indoor temperature, consider switching your thermostat to on or circulate. If you still have temperature control issues, reach out to our team of certified technicians about regular AC maintenance.
FAQs
Keeping your fan on AUTO is the most energy-efficient option. The fan only runs when the system is on and not continuously. There is better dehumidification in your home during the summer months. When your fan is set to AUTO, moisture from cold cooling coils can drip and be drained outside.
Should I set my AC fan to on or auto? ›
Energy Efficiency
AUTO is significantly more energy efficient between the two modes since the fan is only running when your AC is going through its cooling cycle. This takes less power, which is more budget-friendly, with some estimates showing you can save as much as $50 per month just by keeping your AC on AUTO.
Which mode is best for AC cool or auto? ›
Conclusion. In conclusion, auto mode in air conditioning not only helps save energy and reduce costs in the long run, but also improves indoor air quality, offers greater control and customisation, and can be more comfortable for the user.
Should I keep the fan running on my AC? ›
Less frequent starts and stops of the fan can reduce the stress from startup, and potentially help extend it's lifespan. Leaving the fan on 24/7 ensures cleaner air, as the air is pulled through the filtration or UV light system.
When AC is on, should the fan be on? ›
Certainly, ceiling fans accerate the air circulation in your room, it could help the air conditioner to push the cool air around the room, and you will feel more comfortable when you stay in the room, and it is helpful to keep the room warm in winter, it is more energy-saving if you keep the fan on while the AC is also ...
Is it okay to keep AC on auto mode? ›
As a rule, keeping your AC fan setting on auto can save money. Because you're not running the fan all the time, you consume less energy over time. Less energy consumption translates into lower utility bills. The amount of savings depends on the air conditioner and the season.
Should my thermostat be on auto or cool? ›
Keeping your thermostat in the AUTO position means less overall energy is being used—and that reduces your utility bills considerably. Not only that, your air filter will last longer than they will if you leave your fan running continuously—in other words, if you leave it in the “on” position.
Which AC mode is best in hot summer? ›
Cool mode: Ideal for hot days, this mode reduces the room temperature to your desired setting. Dry mode: Perfect for humid conditions, this mode removes excess moisture from the air without significantly reducing the temperature.
What is the best setting to put your AC on? ›
According to the Department of Energy1, 78° Fahrenheit is the sweet spot for air conditioners to balance energy savings and comfort when people are at home and need cooling. But in reality, this is a question that doesn't have a “one size fits all” answer.
Is it cheaper to leave AC on auto or on? ›
Choosing the Auto Setting
If you set your preferred temperature very low, your air conditioner is still going to run longer than necessary. But using the AUTO setting with a reasonable set temperature will keep your energy costs low, especially if you turn your unit off when you're away from home or asleep.
The reason is that ceiling fans push the hot air down, thus intensifying the load on the air conditioning systems. On the contrary, with a ceiling fan, you can raise the Air Conditioner's thermostat by two to four degrees with no rebate in comfort.
Can I leave my AC fan on all the time? ›
Some homeowners naturally worry about the risks of a breakdown if they run the fan all the time, but this will not be a concern for you if your HVAC system was properly installed and maintained.
When to use fan mode in AC? ›
Running your AC in fan mode saves energy because your AC compressor will not have to work. Experts recommend you try this trick during cool weather when you don't need the temperature to decrease. You can also turn on the fan mode after your AC reaches your ideal air temperature.
Should my AC be on auto or fan? ›
Keeping your fan on AUTO is the most energy-efficient option. The fan only runs when the system is on and not continuously. There is better dehumidification in your home during the summer months. When your fan is set to AUTO, moisture from cold cooling coils can drip and be drained outside.
What is the difference between auto and cool on an air conditioner? ›
Compared to the ON setting, the AUTO setting gives you benefits such as: Lower energy consumption. In AUTO mode, the blower fan only runs when necessary, which cuts down your AC system's energy usage. Reduced wear and tear on AC components.
When should I run my AC fan only? ›
Running the blower fan constantly in summer can pull more warm air into your home. As a result, you may need to run your AC system more frequently. But running the fan at night, when it's cooler, can reduce the demand. Since the fan will run only during certain hours, wear and tear may be less of a concern.
When to use AC fan mode? ›
Therefore, the optimal use of fan mode comes in during cooler or less humid times when the AC's cooling function isn't necessary.
Is it better to turn on AC or fan? ›
an air conditioner is significantly more energy efficient. Fans use around 1% of the electricity consumed by air conditioners. You could leave a fan running for a full 24 hours and still use less energy than 15 minutes of air conditioning.
Does running the fan on my air conditioner use a lot of electricity? ›
A typical AC fan motor uses about 500 watts when it's running. Therefore, if you run the fan continuously for a 30-day month (720 hours), you would use 360,000 watt hours (720 x 500) or 360 kilowatt hours (kWh). Therefore, the fan uses about 360 kWh per month in the ON mode.
Does fan mode on AC bring in outside air? ›
When you set your HVAC to “fan” mode, it circulates the air that's already inside your house.
