We are a hvac company that provide air duct cleaning service are minimum charge $400 to do a proper air duct cleaning with 2 techs avg 3-6 hours that includes sanitizing. I get phone calls all day about the $99 your not going to get much of a cleaning for that price it for them to get there foot in the door and up sell that the only way for them to stay in business. Just from my 15 years of duct cleaning experience.
They arrived within the time range I was given, and they even called about 20-30 minutes before arrival, so that was appreciated. They arrived and started bringing some equipment - A shop vac (yea, like you can buy at any hardware store), a handheld vacuum cleaner, and large vacuum that came in on wheels. After showing them the locations of all of the vents in the home and cold air returns, the technician (Simon) started going over a few things with me about their plan for cleaning and showing me the dust & dog hair build up in one of the vents. After showing me that, he started to try to up-sell me on additional services. That additional service was to insert a 'brush' that would agitate the dust/pet hair and allow for the vacuum to get everything out of the vents.
I purchased one of those Amazon air duct cleaning coupons for 49.99. When the company showed up, they removed the vent closest to the air intake and immediately told me I needed $1800.00 for all new duct work. They said they could not clean the system until new duct work was installed. I thanked them and said I would give them a call. The only call I made was to Amazon to get a refund. I know I didn’t need new duct work. Be careful to not fall for unscrupulous salesmen and their pitches and scare tactics.
Air duct cleaning service providers may tell you that they need to apply chemical biocide to the inside of your ducts as a means to kill bacteria (germs) and fungi (mold) and prevent future biological growth. They may also propose the application of a "sealant" to prevent dust and dirt particles from being released into the air or to seal air leaks. You should fully understand the pros and cons of permitting application of chemical biocides or sealants. While the targeted use of chemical biocides and sealants may be appropriate under specific circumstances, research has not demonstrated their effectiveness in duct cleaning or their potential adverse health effects. No chemical biocides are currently registered by EPA for use in internally-insulated air duct systems (see Should chemical biocides be applied to the inside of air ducts?).