• If your suspect that molds are actively growing in the ducts. The obvious symptoms are musty odor from vents. In some cases you can also see a strange discoloration at the vents.
• Sometimes rodents and vermin use ducts to get into your house. If you see rodents or vermin in the house, always check out the ducts. They infest them with droppings and urine trails. When cleaning the ducts the urine trails have to be eliminated too so they do not trace them back to reach your home.
• Small puffs of dust come out of vents when you put on your HVAC. It is a sign that gunk has reached close to your vents.
• If you are moving to a new house you should wait and get its ducts cleaned. In case you have a confirmation from the previous owner that it was cleaned within the last three years, you can drop it.
• If you getting a new house built or re modelling the existing one, get your ducts cleaned before occupying it. The debris from the construction, saw dust, and dry wall dust settles in the ducts unless they were sealed during that time.
• If you have pets in the hours or any family member has allergies from dust, getting your ducts professionally cleaned is a good idea.