When running the AC, should the fan be on auto or on?

Author: Nat Ziemann  |  Last update: Wednesday, July 30, 2025

This means, that in turn, when your setting is turned on auto less electricity is used. When your fan and air conditioner are running all the time, more electricity is produced. All in all, it is better to leave your air conditioner's fan on auto, instead of “On” at all times.

Should I set my AC fan to on or auto?

"AUTO" is the more energy-efficient option, as it runs the fan only when heating or cooling is actively needed. "ON" keeps the fan running continuously, which can help with air circulation and filtration but may consume more energy.

Is it okay to run AC in auto mode?

Yes, Auto mode is intended to save energy. The air conditioner can conserve energy and save you money on your energy bills by automatically adjusting the temperature and fan speed based on the ambient conditions and the presence of people in the room.

Should I keep my HVAC fan on my auto?

Pros for “Auto”: If you set your furnace fan to “auto,” the fan will only run when the system tells it to in order to keep your home as warm as you want it based on your thermostat settings. This means it's consuming less energy than when it runs non-stop, which means lower furnace bills.

When AC is on, should the fan be on?

By using the fan, the Ac need not be on a very cold setting which costs more money. Conclusion: Using Fan along with air conditioner results in the following: Faster cooling – Fan helps to cool your home faster.

Radiator and A/C fan turns ON as soon as the car is turned on

Which mode is best for AC cool or auto?

Auto mode is ideal for homeowners who want to maintain a consistent temperature in their homes without having to constantly adjust the settings.

Is it OK to keep AC on fan mode?

Yes, it is perfectly fine to keep your AC in fan mode. This setting allows the fan to run continuously, circulating air without using the compressor to cool it. This can be particularly useful during mild weather or when you want to save energy by not cooling the air but still need some air movement.

Is it OK to leave 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.

Should I set my thermostat to 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.

Why is my AC constantly running on auto?

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 ...

What does fan mode do in AC?

Understanding the Fan Mode

What does the fan setting on an air conditioner do? It activates the unit's fan to circulate the existing air in the room without engaging the cooling mechanism. This way, it helps in creating a fresh ambiance without significantly altering the room's temperature or humidity levels.

Is it more cost effective to keep AC on auto?

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.

Should I keep my thermostat fan on or auto for humidity?

Leaving your AC fan set to ON allows the moisture in your home to accumulate and reach mold-growing levels of humidity. To ensure that you and your family stay cool and healthy this summer, keep your AC thermostat fan setting to AUTO.

What are the disadvantages of auto mode in AC?

AUTO Setting Disadvantages
  • Hot and Cold Spots. The air distribution throughout the house may be uneven, leaving some areas colder than others. ...
  • Limited Air Circulation. ...
  • Blower Fan Wear and Tear.

Should I keep the fan running on my AC?

Pros of Keeping Your Fan On

First, running fans contribute to even temperature distribution. This reduces the hot spots in your house. Hot spots occur when an area doesn't receive the same temperature-controlled air as other rooms. You'll also enjoy improved air quality in your home.

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

Should my AC fan be on auto or on?

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.

What mode do I put my air conditioner on?

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 mode should my thermostat be on?

You'll want to have your thermostat set to heat mode in the wintertime and air conditioner auto mode in the summertime. In order for your system to run on auto mode, you'll need to have either the heat mode or cool mode on. This way, your thermostat knows whether to turn on the furnace or the air conditioner modes.

Why should we not use fan while using AC?

It only makes you FEEL cooler because it's moving air over your skin, carrying the heat away from your body. This is the wind chill factor you hear on the Weather Channel so often. So it's doing nothing to lower the temperature in your home, meaning your A/C will run just as long whether the fan is on or not.

Is it OK for your AC to run all day?

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).

Can I run just the fan on my AC?

You can run the fan independently of the AC by switching the fan to “Fan On,” which will keep the blower fan running whether there's a demand for cooling or not. The AC can still come on, but you'll have continuous air circulation when it's not. You can also shut the AC off completely so only the fan runs.

Is auto mode good for AC?

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.

Why does my air conditioner keep switching to fan mode?

If your unit is low on refrigerant, it won't be able to cool off the warm air, forcing the AC fan to run more often. If you notice warm air pushing through your vents, this may indicate low coolant levels. Most often, refrigerant leaks from an AC coil.

Is it better to leave AC at a set temperature?

If You're Leaving Home for the Day or Weekend ...

"It's more energy efficient to keep the unit on but turn the temperature setting up," she advises. Turning off the AC unit during the day is not necessarily a bad thing — it is a myth that the AC unit has to work extra-hard to cool off a hot house.

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