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Why Is My AC’s Airflow Suddenly Weak? Answers from a Sarasota Tech

If you’ve noticed that your air conditioner’s air flow suddenly went from strong to weak, you’re probably pretty annoyed (and hot).

Reasons for weak AC airflow include:

  • A clogged air filter
  • Frozen evaporator coils
  • Leaky or blocked air ducts 
  • Problems with the AC blower

We’ll go through each of these issues and explain why it’s restricting your airflow, how to tell if this is your problem and what to do to fix it.

A clogged air filter

Why it restricts airflow:

Your air conditioner can only put out as much air as it “breathes in” through the return vents. But a clogged, dirty filter limits the amount of air your AC can pull in from your home. 

Imagine trying to breathe with a heavy blanket over your mouth and nose. It’s a struggle, right? That’s basically what a dirty air filter does to your AC.

What to do:

Check and change your air filter regularly. When the filter looks like the right filter in the pic below, change it.

HVAC air filter comparison

Left: clean air filter, Right: dirty air filter

Not sure how often you should be changing your filter? Here’s an article that will answer that question, “How Often Should I Change My AC’s Air Filter?” It Depends on This Factor.

Also, check your return vents. Are there any pieces of furniture, clothes, decorations or plants blocking them? If so, move them to another area of the house, to make sure that your return vents are able to pull in the amount of air needed.

Frozen evaporator coil

Why it restricts airflow:

Your air conditioner cools the air inside your home by passing it over cold evaporator coils. But if those coils are frozen over, it basically blocks the air passing over the coils and into your duct system. This blockage results in a significantly weaker air flow.

Several things can cause your evaporator coils to freeze over, including:

  • A dirty air filter or blocked return vent
  • Dirt on your evaporator coils
  • A refrigerant leak

What to do:

  1. Check your evaporator coils. The first place they’ll freeze is inside your air handler. Note: Your air handler is usually located in a closet, attic or basement. 
  2. If you see ice forming on the lines or if they’re already completely frozen over, turn your thermostat fan to “ON” mode instead of “AUTO” to help your refrigerant lines thaw (make sure to place a large plastic tray or tupperware underneath frozen coils to catch the melting ice).
  3. Check and change your air filter if needed. If the airflow doesn’t improve and your coils still freeze over, have a professional inspect your system for refrigerant leaks. If you have a leak, they’ll be able to find it, fix it and recharge your system.

Leaky or blocked air ducts

Why this restricts airflow:

Your air ducts deliver cool air throughout your home. So, if there are any holes, leaks or blockages within the duct system, you’ll notice a decrease in the amount of cold air coming from your vents.

Leaks in the air ducts basically “steal” from the amount of air that can be delivered into your home.

Note: This article talks about a sudden loss of airflow but duct issues usually develop over time. So, if you find that your airflow dropped all of a sudden, air duct problems are most likely not your issue unless you had work done recently

Oftentimes, home construction or a tech working on or near your ducts can result in kinks in flex duct or damaged, leaky ducts.

What to do:

Have a professional inspect your ductwork. They’ll be able to determine if there is anything inside the ducts (dirt, animals, etc) that may be blocking airflow. They’ll also check for leaks and seal any trouble areas to get your airflow back to normal.

Problems with your AC blower

Why this restricts airflow:

Your AC blower is located inside your air handler (inside unit) and is a very likely culprit when it comes to loss of airflow. It’s the “fan” that pushes all the cold air through your ducts and into your house. Without this strong push, airflow would be dramatically reduced.

Some blower issues that restrict airflow include:

  • Excessive amount of dust or dirt on the blades
  • Bad blower motor

What to do:

  1. Turn off the AC.
  2. Locate the blower motor inside your air handler. If it’s covered with dirt you can try to clean it by wiping it with an old rag or toothbrush. Be very careful not to get your fingers caught in the blades as the fan will most likely rotate easily.
  3. Turn the AC back on. 
  4. If the airflow is still weak, you’ll need to have a professional inspect the blower motor for other issues.

AC still not blowing hard? Get help from a Sarasota AC pro

If your air conditioner still isn’t blowing enough air as it used to, we’re here to help.

Contact us today and we’ll send over a professional air conditioning technician who can inspect your AC system.

We’ll get your air conditioner back to its normal airflow in no time.

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