Is fan on bad for AC?

Author: Glen Lang DVM  |  Last update: Saturday, November 22, 2025

Running the Fan Continuously vs. Anything that runs 24/7 will deteriorate faster than something that has rest periods. Even the ongoing stops and starts when you set the fan to auto are less damaging than what happens with months or years of constant use.

Is it OK to keep fan on while AC is on?

Yes it is a good idea to run the ceiling fan with AC on. It will ensure that the cold air circulates quickly in the room and help bring the temperature down quickly. In addition, you might not need to run AC in full blast and low temperature.

Is it okay to keep AC on fan mode?

They should not be left on all the time. Some of the more advanced thermostats might use the fan to better circulate the air post-AC or heat running or pre-cool the home a little by running the fan. But in normal operation, it only runs with the furnace or AC does.

Is leaving the fan on bad for AC?

Leaving your Air Conditioning Thermostat fan setting on RUN instead of AUTO will cause mold damages to your home and contents. It's nothing something that will happen overnight, but leaving the fan on for months, especially during the summer, will cause you to have mold problem.

Is it good to run the fan on your air conditioner?

Comfort enhancement: Using a fan alongside an air conditioner can create better airflow and improve overall comfort. The fan's breeze can provide additional cooling sensation, especially when directed towards occupants or areas that need extra airflow.

Why should we use a Fan with our ACs?

Why not use AC and fan together?

Answer: You can— and should— run your A/C and ceiling fan together. Doing so can help lower your cooling costs each month, but only if you're using them right.

Is it OK to run AC fan all night?

The fan will constantly blow air into your room if you have the thermostat turned “ON.” If it is on “AUTO,” it will only turn the fan on when heated air needs distribution. So yes, running HVAC continuously throughout the day and night is perfectly safe!

Is it bad to keep a fan on 24/7?

A ceiling fan is made up of different parts and pieces, and they will wear out over time. Sure, your ceiling fan can run throughout the day and night without issue, but running it for several days or months on end may not be the smartest choice and will reduce the overall lifetime of your fan.

Does putting your AC on fan save money?

The blower fan uses around 500 watts per hour to run. That's a huge difference! This is why running only the fan (regardless of which method you use) to help keep cool can save you significantly on your energy bills. Of course, the fan on its own doesn't have the cooling power of the air conditioner.

How often should a fan run on an AC?

Your blower motor circulates air through the furnace and can provide uniform temperatures. Many people leave their HVAC fan on all day, while others opt for two to three cycles per hour, ranging from ten to 25 minutes, depending on how close to heating or cooling temperatures they are.

Is it better to leave AC fan on or auto?

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.

Is it cheaper to run AC fan only?

While it is true that the fan alone uses less energy than the AC, leaving it on will almost certainly result in higher utility bills. Running the fan constantly also increases your system's maintenance needs. That's because the more you run the fan, the faster your filter will get clogged.

Should you run your AC at night?

As long as the weather outside isn't excessively hot or humid, keeping your AC switched off while you sleep is a great way to reduce your energy costs. In fact, even in the nighttime temperatures are still in the 80s, this is still a good option as long as it isn't too humid outside.

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.

Will leaving a fan on cool a room?

Ceiling fans circulate air in the room by pushing it down. However, they can not lower the temperature like a window fan or AC unit. But they can still cool you down. That's because their breeze creates a slight wind chill effect that can help sweat evaporate from your skin, which cools you down.

Does leaving the AC fan on 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.

Is leaving fan on bad for AC?

Cons of Keeping Your Fan On

A running fan uses lots of electricity to cycle. Plus, you'll decrease your AC's efficiency during the hot summer months. Your vents could blow hot air into your home, increasing your unit's regulation cycling. This will also greatly increase your energy bill during hot or cold seasons.

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.

Does turning fan AC increase your bill?

A constantly running fan will increase your utility bills and produce more humidity in your home because it will just blow warm air around without the AC absorbing moisture and heat.

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.

Is it OK to sleep with a fan on every night?

It can cause coughing fits in the night

Similarly, this irritation can cause excess coughing. As we've mentioned, running a fan all night long dries out the air in your room. Breathing in this dry air can irritate your throat and lungs, causing you to wake up coughing throughout the night.

What happens if a fan is on for too long?

–Running fans for long periods could cause them to overheat.

Fans start to get hot when the air is pushed out of the blades, but this only lasts a short time. It will cool down quickly.

Should I keep the fan running on my AC?

Pros to Running Fan on Air Conditioner Continuously:

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.

Is it expensive to run AC fan all day?

For all the upsides of a constantly running fan, there are some downsides. The most significant is the increase in energy usage and the subsequent higher bills. When you're trying to cut expenses, keeping the AC fan on 24/7 isn't helpful and will probably cost you more.

How long can AC run continuously?

In general, wall and window air conditioning units with smaller capacities can typically run for up to eight hours at a time before they need to rest. Larger wall and window units have a longer running time of around 10 to 12 hours, depending on their cooling power.

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