Recent Review: Their crew arrived promptly at 7:00 am. Carlos explained what each crew member would be doing. They increased the insulation in my attic. They also discovered that the ducts had been attached to the vents with plain duct tape. The duct tape had become gooey due to heat and had slipped off the vents in many places. This allowed out side air and dust to enter, spreading dust out of the vents. It also allowed cooled air to escape into the attic. The corrected all of the duct work connections. Jeff came to check the work upon completion. He ran tests to verify that the work had been done correctly, and he replaced all of the "regular" light bulbs with cal bulbs. All of the work was done quickly and neatly.
All of you have dentists, you have doctors, you have preachers, you have mechanics. You don’t have to know everything about everything but you have to have people in your life that you can trust. Don’t just open up the phone book and pick a mechanical (HVAC) contractor. Call your friends and family and ask for referrals. There are no black and white (scam or not a scam) answers here.
If you suspect a mold problem — either because of visible growth or a musty smell consistently coming from supply vents — cleaning ducts won’t do much good if it doesn’t eliminate the mold. Mold begins with a moisture problem, and the ducts themselves are unlikely to be the source. The most likely culprits are the cooling system’s evaporator coils, which your heating and air-conditioning contractor — and most duct-cleaning companies — can inspect and maintain. Leaky return ducts can also introduce moisture. Again, if you suspect a mold problem, consider having a service company inspect the duct system for leaks.
Some research suggests that cleaning heating and cooling system components (e.g., cooling coils, fans and heat exchangers) may improve the efficiency of your system, resulting in a longer operating life, as well as some energy and maintenance cost savings. However, little evidence exists that cleaning only the ducts will improve the efficiency of the system.