What Causes Low Airflow in Air Conditioning Units?

Low airflow is a common problem many homeowners experience. Your AC unit may be experiencing airflow issues for numerous reasons.

To best get to the bottom of the problem, professional HVAC technicians can diagnose exactly what’s causing your low airflow and fix the problem to enable your air conditioning unit to run optimally all season long.

Below, our team providing air conditioner repair at Crew Heating & Cooling in Humble, TX, discusses airflow issues and their symptoms.

What Is Airflow?

Airflow is the movement of air throughout your home’s central vents. The driving force of airflow is a difference in pressure. Normal atmospheric pressure is 14.7 psi at sea level. Air tends to move from a higher-pressure area to a lower-pressure area, and the velocity of movement relates to the degree of pressure difference. Normally, conditioned air moves at a velocity of 1000 cubic feet per minute.

The air flowing through a duct in your HVAC system needs regulation by a pressure difference as well as system resistance. Friction in the duct slows down airflow.

An HVAC technician will measure the air pressure in your ducts in inches water gauge (inches wg) using a basic device like a water gauge or electronic nanometer. 

Common Culprits for Low Airflow

If you notice low-pressure airflow, it’s time to figure out what’s causing the restriction. Common reasons air conditioning units experience low airflow include the following. 

Dirty Air Filter

One of the most frequent reasons homeowners experience low airflow is dirty air filters, which trap debris, particles, dust, and allergens from circulating throughout your home. However, when these air filters get dirty and clogged, they don’t create an environment for adequate airflow. 

Since a dirty air filter is likely filled with dust and particles, your air filters require replacement every one to three months to prevent them from restricting airflow. Be sure to change your AC filter regularly.

Leaky Air Ducts

Another reason for poor airflow is when your air ducts have cracks, leaks, and small openings that allow air to escape. As the cool air runs throughout your home’s ductwork, any minor cracks or holes reduce the amount of cool air that comes through your vents. 

Sometimes, your air ducts can also be dirty. When your air ducts are filled with debris, then dust and other particles clog the air ducts, causing friction and preventing proper airflow. Opt for professional duct cleaning services from a certified HVAC company to best care for your ducts.

Damaged Fan

Sometimes the blower fan inside your AC unit gets dirty or damaged, causing it to become sluggish over time. When this fan isn’t working appropriately, it may not be pushing adequate air throughout the vent system. 

If an HVAC expert determines it’s a fan issue, they will clean the grime off the fan or replace the unit entirely. 

Blocked Outdoor AC Unit

Your outside AC unit sometimes gets surrounded by outdoor debris such as leaves, dirt, and sticks that may gradually accumulate and block the air conditioner from pulling in adequate levels of air. When this occurs, it affects the airflow and creates a fire hazard because your AC unit is working harder than it should be, possibly causing it to overheat. This problem is easily fixable by keeping the area cleared away around your air conditioner.

Low Refrigerant Levels and Frozen Coils

Refrigerant is the liquid inside your AC unit that cools off the air before pushing it throughout your home. If you have low refrigerant levels, your vents may barely push out the air. 

The same thing occurs if you have frozen evaporator coils. Without functioning evaporator coils, the air can’t pass through them and becomes blocked. When this happens, you’ll experience poor airflow.  

Signs That Your AC Unit Requires Attention

Maybe you’re unsure if you require professional attention, and you’re looking for signs that indicate you need  to call for service. Here are some telltale signs you should pay attention to: 

  • Noises coming from the unit, like whistling, grinding or squealing
  • Blowing warm air
  • A temperature in the house that doesn’t match the thermostat
  • Not enough airflow
  • Odors coming from AC 

Always Hire Trained HVAC Professionals

No matter the problem you’re dealing with, air conditioner units require trained and qualified repair technicians. At Crew Heating & Cooling, we ensure quality service for every customer in East Texas.  

We offer comprehensive heating and cooling services like maintenance, repairs, and new installations of units, air filters and purifiers

Call our team at Crew Heating & Cooling today at (832) 345-9932 in the Greater Houston area!

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