How Do I Know If My Air Ducts Need to Be Cleaned?

If your air ducts have mold growing in them, are infested with insects or rodents, and if the surfaces in your house get covered in dust immediately after you have cleaned them – then you might want to get your ducts cleaned.

By the way, you should also consider getting the HVAC system cleaned in case your house had recently undergone a major renovation or if you have noticed that your energy bills have gone up without an obvious reason.

There are quite a few problems caused by dirty ducts. While it still hasn’t been proven whether or not the dust in the system can affect the health of the members of the household, we know for sure that dust and dirt restrict airflow. As a result, your HVAC system won’t be able to cool or heat the air as effectively.

Are you asking yourself ‘how do I know if my air ducts need to be cleaned?’. To make things a bit easier for you, we have come up with a list of 6 signs of dirty ducts.

6 Signs that Your Air Ducts Need to Be Cleaned

Dust On the Surfaces

The easiest way to check, if your air ducts have any dust is to open one of the covers and look inside. It is okay for the ducts to contain some dust, but if you spot a lot of debris, dirt, and matted dust, then you might have to call the professionals.

Here are a few other dust-related signs:

You see dust coming from the air vents

If you see a puff of dust coming out of the vent every time you switch the air conditioner on, then your air ducts are dirty.

Warning! A smoky smell might be an indicator of a clogged air duct or a mechanical issue. In such a case, you should try not to use the system, until a technician gets a chance to check it.

Your house is always dusty

Your cleaning schedule has not changed, but you have noticed that your house started getting dirty much faster? The chances are high that your air ducts are so dusty that the particles are coming out of the vents and are then setting on all the surfaces in your house.

Mold/Musty Odor

A lot of people who have air conditioning installed know that condensation can become a great problem. Moisture, in its turn, leads to the growth of mold.

You may be able to notice mold around the vent covers, but, unfortunately, this thing usually starts growing in the parts of your HVAC system that are not easily accessible.

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How to find out, if you have mold growing in your air ducts? A musty odor can become an indicator.

Bear in mind that mold can cause various respiratory issues, so getting rid of it (and tackling the root cause of the growth) is extremely important. 

The House Had Undergone a Major Renovation

Any kind of construction works can get very messy. And, of course, the dust and dirt will find their way into the ductwork.

Unfortunately, remodeling and construction dust are a bit different from regular dust as it can contain toxic particulate matter. 


Chewed-up materials, unpleasant smells, droppings, and nests are indicators of a ductwork infestation.

Squirrels, mice, and different insects can find plenty of ways to enter the ductwork.

Bear in mind that an infestation can’t be cured only by air duct cleaning. You might have to take other measures as well.

Rising Energy Costs

Even though energy costs are constantly rising, you still know what to expect from your bills every month. But if you have noticed that the sum has recently skyrocketed, then dirty air ducts might be to blame. 

To maintain a comfortable temperature with clogged ducts, your air conditioner and furnace would have to work much harder. And this, of course, will affect the electricity bills. 

Hint: any leaks in the ductwork can also result in increased energy consumption. So, you should try to inspect the system for leakage from time to time.

Health Problems

More researches have to be conducted on the topic, but some experts think that dirty air ducts can lead to itchy skin, respiratory infections, asthma flare-ups, and allergies. 

If you have noticed that now your family has to deal with more health-related problems than usual, then you might want to get the air ducts cleaned as soon as possible. 

How to Prevent Duct Contamination?

Thankfully, air duct contamination can be prevented.

According to the EPA, it will cost you anywhere between $400 and $1.500 to properly clean the HVAC system in an average-sized home. The NADCA recommends air duct cleaning every 3-5 years.

However, if you follow the tips below, you might not need to book a professional cleaning that often.

  • Make sure to change HVAC filters and clean coils according to the schedules recommended by the manufacturers.
  • Try to maintain great housekeeping in occupied spaces.
  • Ensure that various contaminated sources are not located close to the air intakes.
  • Regularly inspect the ductwork. Simply visually inspect the air ducts from the outside and sometimes open the cover and have a peek inside. 
  • Don’t leave the system on during building renovation and make sure to carefully seal ductwork when any kind of works are taking place. 

Also see: Does outdoor humidity affect indoor humidity?

Things You Should Know Before Hiring a Duct Cleaning Contractor

Bear in mind that duct cleaning should only be undertaken if all other measures have failed to work. In a lot of cases, it will be unnecessary to clean the whole system. Sometimes, simply replacing an old filter can do wonders.

The first thing that the professionals have to do is perform a thorough evaluation of the system. During this procedure, the main contaminant source has to be identified. The types and quantity of contaminants have to be confirmed based on simple observation and/or testing.

This step is crucial as it will help eliminate the root cause of the problem. For example, if the main contaminant is mold, an air duct clean will not eliminate the source that is causing the growth of mold. The professionals have to find a way to dry the system and keep it that way before starting the cleaning process.

Unfortunately, if air duct cleaning will not effectively remove or neutralize the contaminant, the affected ductwork might have to be removed.

Warning! You should not attempt to clean the air ducts on your own. Contractors have not only all the necessary knowledge but also the right tools. For example, commercial-grade vacuum cleaners and powered brushes. Cleaning the system yourself might be both ineffective and dangerous.

Also see: How hard is to replace ductwork?

More Useful Tips

  • Ideally, you would want to hire a contractor from a cleaning company that is a member of the NADCA. The companies have to meet certain requirements to become members. This will help you ensure that you are hiring a highly skilled professional that has passed the NADCA Certification Examination.
  • During and some time after the air duct cleaning, all family members have to be out of the house or protected.
  • After the system had been cleaned, place a filter over the grills.
  • The contractors have to be aware of this, but you might want to make sure that the professionals are not using any biocides. The substances may pose various health risks.
  • If there are parts of the fiberglass duct material that are wet or have been affected by mold, they should be removed.
  • Bear in mind that brand new ductwork can contain debris and oil. Before connecting the new ducts to the rest of the system, they have to be cleaned.
  • To prevent the return of mold, you might want to consider getting a dehumidifier. There are whole-home options that you can install.
  • You can also run an air purifier if you want. This device can work together with your HVAC system to trap any airborne particles before they enter the ductwork.

To Sum Up

Hopefully, now you will be able to tell if your air ducts need cleaning or not. The main things that you have to pay attention to include:

  • Dust in the actual system
  • Dust coming out of the vents
  • Dusty surfaces in a space that has recently been cleaned
  • Actual mold and a musty odor can be an indicator of mold growth
  • Different unpleasant smells, droppings, and chewed-up elements left by various pests
  • Rising electricity bills
  • More health-related problems than usual

In case any of the things mentioned above have become an issue, you should consider hiring a professional team that will clean your air ducts.

Unfortunately, simply cleaning won’t always solve all ductwork-related problems. That’s why the experts should carefully examine the whole system and come up with a plan that will help you eliminate all of the issues for at least a few years.

You should also try to prevent ductwork contamination. This will help you save money on air duct cleaning and will simply make your life a lot easier and more pleasant.