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Is A Low Or High AC Fan Speed Better? (Explained & Solved!)

Antonio Forde
Updated: June 7, 2022
5 min read

Most of today’s air conditioning systems offer a fan that can be operated at both a high and low speed.

Find out which is better for specific scenarios and why.

Here’s if a Low or High AC Fan Speed Is Better:

A fan operating at the highest speed possible will without a doubt produce the most airflow in the least amount of time. This, of course, will also come at the cost of noise. Despite that, this doesn’t necessarily mean high speed is the best setting for all situations. Take a very hot, humid day for example. A low setting could be a much more effective option. Why? Simply because it will run longer, removing unwanted moisture while it is running.

Does Fan Speed Affect AC?

Yes, you better believe that fan speed will affect the AC. The fan is an integral component of any HVAC system. How it operates will greatly affect the outcome of the AC.

To start, it is important to realize that a residential or commercial air conditioning system contains two fans.

They would be the outdoor fan (condenser fan) or the indoor fan (air handler fan).

The purpose of the outdoor fan is to remove hot air from the condenser and compressor so that the refrigerant in the copper lines can change from vapor to liquid.

When most homeowners or average Joes refer to an air conditioner fan or an AC fan, they are not referring to the condenser fan. In fact, this is one of the more overlooked components.

When most average individuals refer to an air conditioner fan, they are talking about the indoor fan or the air handler fan.

This is the more noticeable of the two components, as this fan’s responsibility is to force air through the ducts and into the home.

When you stand over or under your vents in the home or office, it’s the indoor fan that moves the air. This is the fan most people refer to simply because it is the one that most affects them.

While the outdoor fan does play a huge role in the overall operation of the AC system, it usually goes unnoticed.

With that established, the discussion about fan speeds can get underway. Most people would automatically assume that the better speed is the highest speed.

This assumption is made by many because of the physical connection. It’s the more noticeable of the two.

Now, imagine two box fans, one blowing on high and one blowing on low. What are you going to notice standing in front of the two?

You’ll notice that the high-blowing fan is forcing out more air at a higher velocity. Just because this is the case it doesn’t necessarily mean the high fan setting is always the optimal option.

Things can, unfortunately, get a bit tricky from this point. To fully grasp the concept, you need industry insight explaining how the fan also controls humidity.

The simplest way to think about it is by understanding that an air conditioner’s job is not just to specifically satisfy a temperature setting on the thermostat.

When operating properly and efficiently, the indoor air conditioning fan should also remove humidity. Think about setting your thermostat to 75 degrees F in the summer.

low-or-high-ac-fan-speed_adjusting-ac-temperature

When the temperature in the home rises to 76 degrees F the system will startup. Imagine one system running on the high setting compared to the same one running on the low setting.

The higher setting is going to bring the temperature back down to 75 degrees F faster, causing the thermostat to satisfy and shut off.

This is where most would assume that the high setting is more efficient because it forces the thermostat to reach 75 degrees F faster. And this is true in certain respects.

However, if the fan shuts down too fast it might not remove all the humidity in the home to make it feel comfortable.

If this is the case, it’s going to cause the homeowner to visit the thermostat and turn down the temperature even further.

When the fan runs at a slower speed it’ll run longer, removing more humidity from the air.

This might take a little longer to satisfy the stat, but the process will force the system to remove more humidity during operation.

Since humidity is best described as the degrees to which the air feels, you’re always going to want to remove as much of it as possible.

If properly sized and functioning properly, your indoor fan will already be set to the most efficient settings possible.

If you are trying to tweak your fan to satisfy the thermostat or make it more comfortable in the home something is wrong.

There could be something physically wrong with the fan motor or its squirrel cage. This could also be a blockage of air in the duct system somewhere or the unit itself.

Calculating and measuring airflow can be extremely technical and difficult. Therefore, it is best to work with a professional to make sure your unit is functioning properly.

A guy adjusting AC thermostat

Does Higher Fan Speed Affect Electricity Consumption?

If you think fan airflow is complex, you’ve yet to touch the surface. Although there are some simple aspects to wiring, electrical currents and circuits are demandingly complicated.

According to industry experts, 90 percent of air conditioner breakdowns are due to wiring issues.

Add to that the fact that just about everything in an air conditioner runs on electricity, and you can imagine just how hard it will be to trace these circuits.

This is not to even mention the fact that electricity is extremely dangerous. Electrical shorts can cause fires and it only takes a single amp traveling across the heart to make it stop.

Most basic AC systems produce anywhere from 30 to 40 amps. To muddy things even further, a fan operating on high doesn’t consume more electricity than a low running fan.

They consume the same amount of energy. The reason for this is extremely complicated and technical.

You’ll feel like you need an electrical engineering background just to understand the theory.

However, the easiest way to think about it is in terms of voltage drop, not voltage being applied.

When you change your fan settings, you are changing the voltage drop rather than the voltage applied.

Sources:

AC Designs

Priority Energy

Written by
Antonio Forde
I'm the head-writer @ Ask The Home Geek (or, in plain English, I'm the guy writing & editing the majority of the content here). Current learning project: Korean.
Have any questions? Write us a message.
Antonio Forde
I'm the head-writer @ Ask The Home Geek (or, in plain English, I'm the guy writing & editing the majority of the content here). Current learning project: Korean.