Should You Keep Your HVAC Fan On or on Auto?

Have you ever moved from one area of your home to another and felt like you were stepping out into the Sahara sands from a nice, breezy beach? If the answer is true, you must turn on the HVAC fan to correct this temperature anomaly.

The fan part of your HVAC (heating, ventilation, and air conditioning) system may be operated using your thermostat. HVAC blower fans move the air in a space and eliminate hot and cold areas until the thermostated temperature is reached.

There is much discussion regarding which of these fans' two operating modes—Auto or On—works better. However, each of these settings has pros and cons, so it's impossible to say whether you should leave your AC fan on or off. Additionally, the most recent smart thermostats provide customizable fan settings!

Discover which HVAC fan setting best suits your needs by reading on.

HVAC Fan Modes – Auto & On

HVAC fans offer ventilation, support indoor air quality maintenance, and improve thermal comfort. Let's examine the specifics of Auto and On mode, how they each function, and which one you need to pick.

What Is Meant by the ‘On’ Mode?

The "On" setting implies that your HVAC fan will operate continuously. This option suggests that even when the AC is not heating or cooling, the fan in your HVAC system will run continuously.

There are certain benefits and drawbacks to continually operating an HVAC fan.

Pros of Using the ‘On’ Feature

1. Increased Life Span

By keeping an AC fan running, it won't have to start and stop repeatedly, which relieves the fan's stress. You wouldn't believe it, but this procedure can help your HVAC blower last longer.

2. Fresh Odorless Air

During the spring and fall, temperatures remain mild, particularly in enclosed structures and areas with many shuttered windows. If the air conditioner is turned off in this case, the air will likely be stuffy. Keeping your HVAC fan running might help you maintain clean air and get rid of unwanted scents.

3. Improved Air Quality

Your AC filters will be used more frequently if you have a fan running constantly. Pollen, dust, germs, and mould are just a few pollutants that may be eliminated.

However, the kind of air filters you have placed in your HVAC system and how well you maintain them will determine the advantage you receive from air filtering. Filters may successfully remove most microscopic particles in the air with a high MERV rating.

4. Better Air Circulation

The air that your air conditioner warms or cools cannot be circulated adequately. A fan helps to eliminate any hot or cold patches in your home and improves how the conditioned air is distributed throughout it.

The fact that hot air rises while cold air is close to the ground is another issue with air circulation. This might lead to hot air building up in your home's upper levels, raising the temperature there. To effectively circulate air on higher levels all the time, not just while your cooling is on, keep your AC fan running continually.

Cons of Using the ‘On’ Feature

The drawbacks of running your HVAC fan in "On" mode are listed below.

1. Hot Air in Summer

During the summer, hot air can accumulate in ducts that are positioned close to an attic or adjacent to walls. When the fan is operating all the time, the air in your home is circulated. Your room eventually becomes heated as a result, and the AC has to run more frequently to cool it off.

2. Inefficient Humidity Removal

During cooling, moisture from the air is removed. When air travels across evaporator coils, moisture condenses in droplets on the coils. Droplets of water fall from the coils as soon as the system finishes cooling. You need to remove this water from your house.

The efficient removal of humidity is hampered by the HVAC fan working continually, which causes some of this water to evaporate back into the air.

3. Cold Air in Winter

A cool breeze will come out of your vents when you switch on the fan of your air conditioner in the winter when the heater is off. You continue to feel chilly even if the air temperature is the same.

4. High Energy Bills

Your energy costs will increase if you leave your air handler fan running all the time. When running the HVAC fan solely, an air conditioner may use up to 500 Watts, depending on its size, brand, and length of usage. This can total 360 kWh each month.

5. Frequent Need to Change the Air Filter

HVAC air filters clog more easily when room air is continually pumped through them. The air filter would require more regular cleaning or replacement.

What Is Meant by the ‘Auto’ Mode?

If you set the fan on your HVAC system to "Auto," it will only run when the system is heating or cooling. For instance, when your thermostat reaches the desired temperature, the entire system, including the AC fan, switches off.

Pros of Using an HVAC Fan’s ‘Auto’ Feature

1. Better Dehumidification

Because the HVAC fan turns off in Auto mode as soon as cooling is complete, condensation droplets on coils below might easily flow into the drain pan. The moisture is then safely expelled outside the home. You can achieve the ideal humidity levels in your house thanks to this.

2. More Energy Efficiency

When you set your air conditioner's fan to Auto, it will only operate while the system is cooling or heating. Therefore, the fan works for the shortest time possible. Thus, setting your fan to Auto is more energy-efficient than always leaving it on. You experience cheaper energy costs as a result.

Cons of Using the ‘Auto’ Feature

Even while this mode saves money and offers better humidity management, you could run into some issues with a few things.

1.Breaks Down Faster

The fan motor will regularly switch on and off while your HVAC blower is set to Auto. This will shorten the fan motor's lifespan and create early wear and tear.

2. Uneven Temperature

Without circulation, hot air would continue to climb and cold air will remain in the bottom section of the space, resulting in an unbalanced temperature.

Verdict on AC Fan Mode: ‘On’ or ‘Auto’?

To inquiries like "how long should my HVAC fan operate per hour?" there is no conclusive response." or "Should I set my fan to "Auto" or "On"?".

It is up to you to decide whether to frequently run the fan or set the AC fan to "On" or "Auto," all of which have benefits and drawbacks.

The only thing that matters, though, is how humid your location is. If you reside in an area with high humidity levels, turning on your HVAC fan may result in ineffective humidity removal and mould development. Operating the AC fan on "Auto" is safe in such areas.

However, certain choices can assist you in minimizing the drawbacks while maximizing the benefits!

  • Smart Thermostat: You may establish custom timers for smart thermostats to only operate your fan at required settings. Regardless of the heating or cooling cycles, you may choose how long your AC fan runs every hour.
  • Variable Speed Technology: Another excellent choice for your HVAC system is to use variable-speed fan motor technology. A fan motor with variable speeds runs at various speeds to effectively regulate airflow in your house.

The AC fan continually circulates the air using variable speed technology, but because your system may operate at a lower capacity, it is energy-efficient. It also prevents the system from continually switching on and off, saving energy costs. Consequently, this system offers improved humidity management, extended fan motor life, consistent temperature, and continuous filtration.

Frequently Asked HVAC Fan Questions

When you turn on your air conditioner fan, a number of problems might arise because all air conditioner components are prone to wear and tear over time. You could have concerns about when or for how long the fan should be operating. The most frequently asked questions are answered below.

Why Your HVAC Fan is Not Working?

The following factors might be to blame if your fan doesn't operate even when your air conditioner is on:

  • Dead Capacitor

A tiny, cylinder-shaped part of an air conditioner called a capacitor stores electrical energy and releases it to the system as needed. An air conditioner has several capacitors. The HVAC fan won't operate if the capacitor that supplies power to the fan motor is dead. Therefore, you would have to get it replaced.

  • Burnt-out Motor

Fan motors are susceptible to overheating, and when combined with poor maintenance, the motors become worn out and quit functioning. These require professional replacement and are expensive to fix.

  • Power Issues

Occasionally, the circuit breaker may trip due to overheating. As a result, your HVAC fan stops functioning. This problem may be resolved by simply flicking the switch on the circuit breaker.

  • Dysfunctional Contactor

This component of an HVAC system regulates the electrical flow inside the air conditioning system. These contractors may deteriorate with time and finally burn out. Your HVAC fan may stop functioning as a result of this. Contractors must be properly maintained to be in excellent working order, but if they become worn out you are left with little choice but to have it fixed by an HVAC professional.

  • Air Filter Blockage

The air filters might become clogged if they are not regularly cleaned and changed. The obstruction causes the fan to shut off since it is under increased strain. Cleaning the filters regularly might address this issue.

Why Your HVAC Fan is Not Working?

Yes, leaving your HVAC fan running continually is both possible and absolutely safe. As the air regularly travels through the air filters of the AC unit, it will aid in air circulation and keep the air clean.

Do HVAC Fan’s Bring in Outside Air?

No, the AC blower fan does not often bring in fresh air from the outdoors. It moves the air already in the space to increase circulation and get rid of hot and cold areas.

How Much Does It Cost to Run an HVAC Fan?

A typical 500 watt fan motor consumes 360,000 watt hours, or 360 kilowatt hours, if it runs nonstop for a month (kWh). In the US, a kWh costs around $0.12. Thus, it will total $518 per year or $43.2 every month.

Does the Fan Always Run When the Heat Is On?

If your fan is set to Auto, it will start spinning when the heating or cooling system kicks on. On the other hand, if the fan is in the On position, it will remain on even if your air conditioner is not cooling or heating.

HVAC Fan Speed Too High: What Should You Do?

If your HVAC fan speed seems too high, it might cause complications with the system. Here is what you need to do in this situation:

  • Turn off the power of the system.
  • Next, look in the unit's handbook to find the system's pulley, blower motor, and set screw.
  • To begin, you must unscrew the screw, rotate the pulley counterclockwise, and then tighten the screws.

Take Away

HVAC fans are necessary for your home to have enough ventilation and airflow. If you want to remove hot areas and stale air efficiently, you can opt to turn your HVAC blower fan to the On position. On the other hand, Auto mode is more suited for you if conserving money and effective humidity removal from your area are priorities. Regardless of the fan setting, remember to maintain your HVAC system regularly to ensure optimal operation.

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