How to Tell if Air Ducts Were Cleaned Properly

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Statistics show that about 90% of people spend most of their time indoors. Especially since the Covid-19 pandemic hit. In addition, more and more of us are becoming aware of the importance of indoor air quality. You may easily identify the causes of outdoor pollution, but the causes of indoor air pollution are pretty challenging to identify.

Cleaning the air ducts of your HVAC system can help to ensure the air you breathe is clear, fresh and comfortable.

Most people will call in an air duct cleaning company, it’s hard to see into these ducts, and without specialist knowledge and equipment hard to clean them properly. But how do you know when the air ducts are well cleaned?

There are a few things to look out for:

The Process

Just by looking at the duct cleaning process, you can identify if the cleaning company did a thorough job or not. You can check how they handle the HVAC system and its components, including air ducts, registers, filters, and plenums.

A typical process should involve the following:


First, the staff conducting the cleaning should check the ducts, assess how much buildup is present in them, and confirm the difference after cleaning. Before cleaning, the duct cleaning contractor can use special cameras to identify the buildup’s full extent.

The professionals can also check for any leaks In the ductwork, carrying out repairs and replacements as necessary.

Creating Negative Pressure

The contractor may then use a special duct cleaning vacuum to remove the debris and dust from your duct-work. They follow some processes before the vacuum machines can start the suction. The steps followed include:

  • Hooking the hose of the vacuum collection device to the duct, close to the air handler. The process involves making a hole through the duct (near the furnace), inserting the hose then sealing as tightly as possible.

It is important to note that the HVAC system has two sides, the supply side and the return side. The supply side contains ducts sending air into various rooms in the hose, whereas the return side has ducts that return air to the air handler. These are separate sides, and the cleaning professionals have to conduct the duct cleaning process on both sides.

  • Using an adhesive to seal each register. This is to ensure that the registers in every room are covered to facilitate the effectiveness of the vacuum collection device.
  • Turning on the vacuum unit. This creates negative pressure, allowing the vacuum collection device to suck the debris and dust present in the duct-work. The particles are first brushed and blown loose.

Agitating the Dust

After the system creates negative pressure, the technicians uncover every register and clean the ducts one after another. If the technician hurries from one register to another, it is proof of a poorly done job. Dust may end up being blown back into the room.

A professional cleaner will take time, switch brushes and other tools to ensure that all the dust gets dislodged so that the vacuum collection device can suck it.

Cleaning the Rest of the HVAC System

A professional air duct cleaner will clean every other HVAC system component, not just the ducts including the drain pan, evaporator coil, and the air handler’s blower motor. After cleaning the components, the technician will change the filter is required. This helps to improve the air quality in your home while increasing the lifespan of the HVAC system.

1. Inspect the Duct Interior

Before inspecting the interior of the air duct, it is good to know that some AC plenums have UV lights installed. You will have to turn off these lights before starting the inspection since they can damage your eyes. The purpose of the UV lights is to prevent the growth of mold and bacteria.

Remove the cover of the register and use a flashlight to look into the ends of the ducts. You’ll need a reasonably strong light. Remember only to remove the register covers if you are sure about reinstalling them. It may be challenging to return the covers and screw them on properly.

Inspect the bottom of the ducts and ascertain that there is no dust or other debris. If you notice any, then the cleaning job was not thoroughly done.

2. Check the Vent Covers

It is good to ensure that all your registers are clean. A good cleaning company will ensure that all the register covers are well cleaned. Any dust on the registers may be an indicator of dirty ducts. Remember that removing the register covers may be easy but you may find it challenging to return them. It is usually hard to align the screws with the screw holes.

3. Check the Access Doors

Typically, the air duct technicians cut a hole in the ductwork near the furnace and sealing it when they complete the cleaning process. If the technicians did not cut any hole, your ducts are not clean. You have to check to ensure that they sealed the hole properly because failure to close it completely will cause costly problems afterwards.

4. Check the Functioning of the AC and Furnace

You have to ascertain that the furnace and AC are functioning well after the cleaning process. Unqualified technicians will cause damages to your furnace or AC. If you find any damages, you will hold them accountable.


Once you have conducted the above checks and ascertained that there is no problem, you can be sure that the cleaning company did a good job. You can have peace of mind knowing that your air ducts are clean.