The clearest sign that your air ducts need to be cleaned is if you can see dirt, debris, or dust on your air vents. Additionally, when your HVAC system starts running, there is not supposed to be dust coming out of the air vents. If you see visible contaminants on your air registers or blowing from your air vents, this is a sign that it is time to clean your air ducts.

If your air filters frequently get clogged, this is another indication that it is time to clean your air ducts. Your air filters are supposed to be changed periodically after a few months. If you are frequently going through new air filters because they are becoming clogged, your air ducts need to be cleaned. It is possible that your airflow is being restricted in your ductwork, which allows excess dust to settle in the return ductwork and air filters. Frequently clogged air filters are a sign that it is time to get your ductwork professionally cleaned.

There should not be a musty smell coming from your heating and cooling system. If there is a strange odor in your house and you cannot locate it, it is possible that it is coming from your air ducts. You can try smelling the air registers to locate if the smell is coming from your HVAC system. An air duct technician will be able to assist you and remove whatever is causing the smell in your ductwork.

Pet dander, debris, dust, and dirt can restrict airflow throughout your house. Dirty air ducts are not efficient at blowing consistent air. If you have noticed unequal airflow in your bedroom compared to your kitchen, for example, this is a sign that your air ducts may be dirty. Your indoor airflow should be consistent in all areas of your home. If not, it is time to clean your air ducts.

A picture of someone screwing an air duct vent into place.

Your utility bills should be relatively stable throughout the year. If you have noticed that your heating and cooling bills are much higher than you are used to, your air ducts could be to blame. When your air ducts are dirty, your furnace and air conditioner have to work harder to keep your home at the set temperature. The harder it takes to heat and cool your home means you are using more energy, which also means higher utility bills. In this situation, it may be necessary to clean your air ducts as well as your furnace.

If your air conditioning coil is dirty, this is a sign that it is time to clean your ductwork. Your air conditioning coil should not be dusty or dirty. If it is, then this is an indication that your air filter is not working as it should. You will want to call in a professional to examine your HVAC system and thoroughly clean your air ducts.

When your air ducts are dirty, this worsens the indoor air quality of your home because dirty air is circulated throughout your home. If your house is frequently dusty, it is possible that your air ducts are blowing contaminants onto the surfaces of your home. If you find yourself continuously cleaning and dusting your home, it is time to call an air duct cleaning professional.

Your air ducts should never start to make unusual noises out of the blue. After living in your home, you start to understand what it sounds like when your HVAC system turns on. However, if you hear noises other than what you normally hear, this may mean your air ducts are not working properly.