How To Check For Blocked Air Ducts And Unclog Them

Your HVAC system blows air into your house through the air ducts. Even if your air conditioning unit is fine, a blockage in the ductwork can lead to cooling or heating issues. Your HVAC may be blowing cool air into your house normally, but a blocked air duct may stop it from reaching a specific room or many rooms. Hire AC repair services to check and remove blockages from air ducts. These are the signs that hint toward the blockage of your ductwork.

Difference Between Blocked And Dirty Air Ducts

However, keep in mind that dirty air ducts and clogged air ducts impact your HVAC system differently. Dirty air ducts can impact indoor air quality, and make the air filter dirty more quickly. On the other hand, blocked air ducts can reduce the cooling or heating efficiency of your HVAC unit in addition to the effects caused by dirty air ducts. More simply, blocked air ducts is a severe form of dirty air ducts.

We will explain the signs for both. Some signs overlap with each other. In both cases, it’s best to clean your air ducts thoroughly.

Signs Of Dirty Air Ducts Of Your HVAC System

Faster Duct Accumulation In The House

When AC’s air blows through dirty air ducts, a lot of dust settled in the air ducts and moves inside the house. Due to this, you will notice that your house is becoming dustier more quickly than before.

However, quicker dust accumulation can be due to an air duct leak or any other part of the house leaking allowing air and dust inside.

Air Filters Are Becoming Dirty More Quickly Than Before

Air filters should be cleaned or changed frequently depending on the type of air filters you’re using. Regardless of the type, if you notice that the air filters are becoming dirty more quickly and you’re seeing yourself cleaning the air filters more than usual, it means the air ducts are dirty.

Dirty air ducts constantly throw dusty air into your house. As air filters are installed to block dust and debris from entering the house, most of the dust sticks to the filters. This makes air filters dirty more quickly.

Similar to the air filters, the air vent covers will also become dusty more quickly if the air ducts are dirty.

Unpleasant Odor Throughout The House

In summer months, humidity can cause mold growth inside the air ducts. If your air ducts haven’t been cleaned for a while, it will increase the risk of mold growth in summer.

When air blow through the ducts where mold is grown, the air will become musty and you will feel a musty odor in your house.

Visible Puff Of Dust When You Turn On The HVAC

If your air ducts have enough dust, you may see a visible puff of dust coming from the air vents when you switch on the air conditioner. This leaves no doubt that the ductwork requires cleaning and you should not delay it.

You Recently Did A Home Improvement Project

Remodels and renovations are exciting, but they also lead to lots of dust everywhere. This dust is blown into air ducts as well which are usually ignored. While people completely clean their houses after renovations, they overlook the cleaning of the air ducts that also received a lot of dust and it’s settled inside the ducts.

Your Allergies Are Worsening

If you’re allergic to dust, you may notice that your allergy symptoms are aggravating. So, if you’re suffering from too much sneezing, coughing, water, or itchy eyes, then dirty air ducts may be blamed and you should have an HVAC contractor Chantilly to check and clean the ducts.

Respiratory Health Issues

The dust accumulating inside the air ducts flows with the air into your house. This makes your indoor air quality poor. Poor indoor air quality can lead to health problems like respiratory issues. Moreover, indoor air quality impacts more quickly on people with asthma more.

Signs Of Blocked Air Ducts

The signs of blocked air ducts include many of the signs we have mentioned in the above section. Below are some more signs of blocked air ducts.

Your HVAC Runs Constantly Or A Cooling Cycles Take Too Long

When one or some parts of air ducts are blocked, cool air won’t flow to every room of the house as it should. This will put stress on the AC because it will work more for reaching the temperature you have set. It can result in your HVAC running constantly or the cooling cycles

An Increase In Energy Bills

Your AC runs constantly or more than normal due to the reason that some ducts are blocked and your home is not cooled efficiently. When your HVAC system keeps working more, it takes more power as well. This leads to an increase in your energy bills. So, if your energy bills are increasing every month, you should get your HVAC unit including the ducts checked by a professional to find out the cause of the problem.

A common reason for this is blocked ducts. However, it could be another reason like dirty air filters, air duct leaks, improper maintenance of the unit, insufficient refrigerant levels, and others.

The AC Is Not Cooling Evenly

When air ducts are blocked, some rooms may not receive air or receive less air. Other than putting stress on the AC and making it run constantly, the temperature in your house won’t be even due to this. So, many rooms may be cool, but one or a few may be warm.

How To Inspect And Fix Air Ducts Blockages

  1. Turn on the heating or cooling of your HVAC system.
  2. Once the fan starts, check the vents in each room. You will feel air coming out of vents in each room. If the air pressure is less or no air at all in a room, the duct getting to that room may be blocked. Let’s say one room in your house isn’t receiving air.
  3. Check the air filter in the vent of the room and clean or replace it.
  4. After cleaning the filters, remove the vent cover and inspect what’s behind the grill of the vent. Air flows through the grill easily, but it can stop bigger pieces of debris stuck inside the ducts. The grill stops bigger debris, but this also restricts or blocks the airflow.
  5. If you find bigger pieces of cardboard, old pieces of air filters, or anything else, take it out and put it in a trash can.
  6. Then clean the area of the ducts again with a brush to remove small dust particles as well.
  7. Moreover, check the whole ductwork as well and make sure that the seams are there and there are no loose parts of duct tape. If you see duct tape near duct seams, remove it and then replace it with metal tape.
  8. Locate and check the butterfly valve of the room as well. Open the valve to allow 100% airflow. If the room still doesn’t receive air, clean the valve.


Air ducts are usually ignored in HVAC maintenance by homeowners. They accumulate dust and debris leading to dirty air ducts and in more severe cases, blocked air ducts. If you spot the above signs of dirty or clogged air ducts, connect with air conditioning companies McLean for cleaning.

Leave a Reply

Your email address will not be published. Required fields are marked *