How To Reduce Airflow From Vent

We’re often only concerned about low air conditioner return air, which is ok because it’s the more common problem. However, too much airflow is just as bad. Besides causing cold and hot spots, it can make indoor conditions uncomfortable. An extremely powerful airflow can even damage the AC. 

How to Reduce Airflow from Vents

  1. Place an adjustable vent deflector over it
  2. Make sure you have the right-size AC and ducts
  3. Check AC the settings
  4. Adjust the supply registers
  5. Adjust manual dampers

Read on to learn common causes of too much airflow, signs to watch out for, and what you can do to remedy the situation. 

How Much should Airflow be Coming Out of the Vents?

Unfortunately, there’s no one right answer. The most important thing is that the air coming out of your vents should be roughly equal throughout the house.

For instance, you want to confirm that your bathroom fan is blowing at least 50 cubic feet per minute. Otherwise, you’re not getting enough airflow. 

However, feel free to keep records or even hire an HVAC technician to evaluate your airflow if you don’t feel comfortable or feel that something’s off.

An anemometer makes it easy to measure air velocity to know whether you’re within the ideal range. The optimal indoor air velocity (measured on an anemometer) is 0m/s.

How Much Airflow is Too Much?

The upper limit is even more difficult to tell. However, the general rule is to feel comfortable enough throughout the home. Whistling noises, pressure imbalance, and excess drafts often point to too much airflow. 

If you decide to measure air velocity in your home to make sure you’re within the ideal range, do everything you can to bring the velocity down to 0m/s. However, even if you don’t have an anemometer, a slight draft during the summer often points to air velocities between 0.8m/s to 1.0m/s. 

This can signify that your air conditioner is blowing too fast or too much air. So, you need to do something about it. 

Dangers of Too Much Air Conditioner Airflow

A stronger-than-usual air conditioner airflow may not be harmful in the initial stages. However, the consequences are more evident as the air velocity increases.

Some of the dangers/damages include;

1. Noise

A whistling noise from your air conditioner and swooshing noises throughout the house are often the first signs that your air conditioning system is blowing too much air.

That whistling sound often results from air forcing through a filthy or blocked filter or a blocked duct or vent. Meanwhile, swooshing noises typically result from the friction between air and objects. 

2. Hot Spots and Cold Spots

You’ll also likely notice hot and cold spots if your air conditioner blows too fast or too hard. You’re probably wondering why. The reason is that fast-moving air doesn’t necessarily mean the air reaches every corner of the room.

The opposite is often true as high-velocity air doesn’t circulate properly. Instead, it forces its way in one direction. As a result, hot and cold spots can cause serious discomfort. 

3. Pressure Imbalance

High air velocity in an enclosed space often results in a vacuum. The good news is that it’s extremely difficult to experience a vacuum in your home because the home isn’t completely enclosed.

However, you’ll likely create excess air pressure in some areas and lower static pressure in others. Pressure imbalance in the home can cause many issues, including health problems. 

4. Compromised Energy Efficiency 

When you experience too much airflow from your air conditioner, the AC is overworking. Either the unit is set too high, thus circulating air very fast, or it’s working harder to overcome obstacles, such as blocked air filters.

Whichever the case, the AC is consuming more energy, most of which goes to waste. The result is higher energy bills. 

5. Compromised Indoor Air Quality

Finally, the air conditioner blowing too fast may also cause poor indoor air quality. First, a strong draft easily stirs up dust, pollen, and dander throughout the house. This can trigger allergies and asthma.

Additionally, fast-moving air makes it difficult to breathe. It can also dry up our mucous membranes, triggering nosebleeds and other unpleasant symptoms. 

Why Does my HVAC System Blow Too Much Cool Air?

It’s never easy to tell why an air conditioner is blowing too fast or blowing too much air. However, the most common reasons are as follows;

1. Oversize AC 

Air conditioners are sized based on the size of the house, your local climate, and your personal needs. As a result, a perfectly-sized air conditioner blows enough air to keep you comfortable and not too little or too much. 

So, what happens if the air conditioning system is too big for your home? It will blow more cool air than you need. 

2. Undersize or Damaged Ductwork

HVAC duct systems are also sized to deliver just enough airflow to keep the home within optimal temperatures like air conditioner units. Thus, a large duct system will pump more cold air than you need, resulting in cold drafts.

Additionally, you may experience problems if the ductwork is damaged. For instance, bent ducts can increase airspeed. 

3. Blower Motor Issues

The air conditioner relies on a blower motor to draw hot/warm return air through the return ducts and push out cold supply air via the supply vents. So, the rotating motor and turning blades determine the air intake and air supply speed. 

Now, imagine that the blower motor or some blades are broken. The blower system would be unable to pump much air into your home. Or, it may push out more air than you need until it’s fixed. 

4. Too Few Vents

You may also not get enough airflow from your air conditioner if you don’t have enough vents. Alternatively, you’ll have to deal with a higher air velocity as air squeezes through the few available vents.

Remember that “too few vents: may apply to a single room or the entire home. Again, an HVAC professional can help you evaluate the situation to determine your next steps.  

5. Closed vents

Finally, if some of your air vents are partially or fully closed, you may experience a higher velocity from the open vents. Why? Because all the cold supply air must now exit via the few open vents or through constricted outlets in partially closed vents. 

This problem mostly happens after the winter season as some people prefer to close some vents during the winter. So, manually check to ensure that your vents are open. 

How to Reduce Air Flow from your HVAC Vents

The good news is that it’s not too difficult to reduce airflow from your HVAC vents. The following are nine tips to consider;

1. Place an Adjustable Vent Deflector Over It

Air deflectors redirect air where it’s needed to ensure even heating and cooling throughout the house. The plastic deflector fits over air vents or air diffusers to direct airflow in the desired direction. 

An adjustable deflector is the best choice as you can point the deflector in a different direction as you wish. The good news is that air vent deflectors are cheap and easy to install. 

2. Make Sure you have the Right-Size AC and Ducts

First, make sure your air conditioner is correctly sized. An air conditioner too large for your home will blow too much air, leaving you feeling uncomfortable. Secondly, ensure you have enough ducts and that they are correctly sized. 

Don’t hesitate to add a new bypass duct if necessary. However, don’t add a duct yourself. Instead, let an HVAC professional handle the matter. 

3. Check AC the Settings

Is the air conditioner set correctly? Is the thermostat working in good condition and set to the correct temperature? It’s important to repair or replace the thermostat if it’s not working correctly.

More importantly, make sure it’s set to around 78 degrees. Setting it lower often causes the air conditioner to work harder. 

If the unit is broken, arrange for an HVAC technician to look at it. Otherwise, you may need major repairs within a few months. 

4. Adjust the Supply Registers 

A small lever on the side of the register moves the brackets inside the registers, allowing more or less air to enter the room. So, move the lever slowly until you reach the desired airflow rate. Then repeat for all the registers in your home. 

Alternatively, replace the registers and grilles with high-velocity models. Fortunately, registers and grilles are affordable and easy to install. 

5. Adjust Manual Dampers

A cooling system damper should never be fully open or fully closed. Instead, you need to adjust the dampers regularly to ensure optimal airflow into the room during heating or cooling. 

To adjust the damper, use the lever to turn it to the left or right. Then monitor the airflow for a while to determine if you’ve hit the sweet spot. If not, keep adjusting the register until you hit the right damper position. 

6. Implement a Zoning System

If your cooling system is blowing too much air or lowing air too fast because you don’t have enough vents, you should consider zoning the house to achieve uniform airflow throughout the home. 

One of the easiest ways to zone your home is using HVAC zoning dampers. A zoning damper creates multiple zones out of an existing HVAC system for even heating and cooling. 

7. Switch to an ECM Blower Retrofit

ECM motors are a lot more efficient than AC motors. They maintain a high-efficiency level, between 65% and 75%, whichever the selected speed.

While modern AC motors can also run at variable speeds, they rarely maintain a high efficiency as the speeds change.

Additionally, an EMC blower retrofit has greater speed accuracy than standard AC motors, thus eliminating the risk of too much airflow. 

8. Eliminate Airflow Restrictions

We saw earlier that restrictions due to a blocked air filter, bent ducts, and dirty coils are some of the main causes of unnecessary fast AC airflow. So, don’t forget to troubleshoot and promptly fix the issues. 

For instance, always use the right size air filters and replace or wash the filter as the manufacturer recommends. Also, duct and clean the air conditioner regularly to avoid dirt buildup in the ducts and vents. 

9. Install Extra Air Vents

If all else fails, you may have to install extra air vents to relieve the existing few. However, beware that installing new HVAC vents is an expensive process. So, don’t make the decision yourself. Instead, call an HVAC professional to determine the best resource. 

Besides costs, finding the best location for the new vents is critical. Otherwise, you may worsen rather than resolve the airflow problem. 


Too much air conditioner airflow is just as bad as too little airflow. It can cause strange noises, hot spots and cold spots, and pressure imbalance throughout the house.

Additionally, it can cause doors to swing back and forth, causing even more noise. Fortunately, you know the most common causes of too much airflow and what to do about it.