2. Examine the return air registers for dust buildup, particularly if there are thick, fuzzy coatings of dust.

3. Pull out the air filter. If the air filter is clogged with dust, then air flow is being choked off. This lets more dust settle and build up in the return ductwork.

4. Open the furnace compartment. Examine the blower fan and motor for signs of dust as well as the furnace controls. The more dust you see, the bigger the problem you have.

5. Look at the air conditioning coil. (You may need to remove a panel.) If the coil is dusty or has dust clinging to the housing walls, then the air filter hasn't been working properly.

Any of these indicators show that your HVAC system and ductwork is being adversely affected by too much dust and dirt.

Top 5 dirty air duct consequences

So what trouble's in a little dirt and dust? Plenty. There are a number of problems caused by dirty ducts, ranging from increased energy costs to health problems:

1. Dirt and dust restrict your HVAC system's heating and cooling. In the winter, dirt-clogged heat exchangers cannot warm the air as efficiently. In the summer, dirt-clogged condensing coils are unable to cool the air as well. These both increase the HVAC systems run time, requiring it to use more fuel and energy to heat and cool your home.
2. Dirt and dust restrict air flow. Let's say your system is doing a fine job of heating and cooling the air. But if the blower fan or motor can't turn because of dirt or the air filter is clogged with dust, then the system can't effectively circulate that properly warmed or cooled air through out your home. It's still going to run longer and use more energy.
3. The longer your HVAC system operates, the more wear and tear it undergoes. Long run times can shorten the overall life time of HVAC systems, from AC compressors to hydro pumps, burners, and motor bearings. You'll wear out your home's HVAC system sooner.
4. Dust contains not only fine dirt, but also dead skin, pet dander, microorganisms from cat litter (toxoplasmosis), and other particulates such as pollen, mold spores, fungi, and even rodent feces. Left to contaminate your HVAC system, it can become a breeding ground for bacteria, mites, and other pests.
5. Dirt and dust spread quicker in a home with dirty ducts. No matter how diligent you may dust and clean your home, fine particulate contaminates, including dangerous allergens, quickly flow from room to room to cover tables, smart phones, and children's toys..

Top 5 benefits of air duct cleaning

Experts advise having your air ducts cleaned every 2 to 3 years to prevent many maintenance and health problems before they start. However, homes with pets or children with allergies should have their air ducts professionally cleaned more frequently than the recommended average. The top five benefits of cleaning your air ducts are:

1. Better and reliable over-all performance from your HVAC system
2. Fewer expensive repairs from wear and tear and longer HVAC system life
3. More energy efficiency, reducing your energy bills
4. Lower likelihood of respiratory and allergy problems
5. Less dust makes it easier to clean and maintain your home's living space

Contact a professional

Cleaning the ducts of your HVAC system can be a do-it-yourself project, with the proper instructions from a trusted online source or a DIY manual. However, for a more thorough cleaning, hire a certified cleaning professional. They will use industry-standard equipment designed to handle the size and volume of all kinds of homes, ensuring cleaner, healthier indoor air in your home.