While it is usually better to get a professional air duct cleaning specialist to examine and diagnose any duct problems you might have, there are some problems you can discover for yourself.
While you are up in the attic at Christmas time pulling down your decorations for the year, take a minute to look at the many ventilation ducts that are probably running through the attic. If those vents are not insulated, then you are losing huge quantities of heat in the winter and cold in the summer to your attic. Because your attic usually is not connected to the HVAC system, it is usually the hottest or coldest place in the house, depending on the season.
2) Blind Alleys: Looking for Vents in all the Wrong Places
A blind alley is a section of ductwork that runs off of the central trunk from the HVAC system and travels nowhere because the end of the duct has been walled off. Blind alleys usually are the result of installation or repair mistakes. At the same time that you have a walled off duct, you probably have a lonely register with no source of heated or cooled air just waiting to be connected.
3) Damaged Ducts or Duct Joints
When sections of duct work have completely separated or wiggled loose to the point where you can see daylight between the seams, your HVAC will struggle. The duct system is supposed to be seamless to ensure that as much air as possible makes it to the house. When you discover such sections of duct work, health risks make it imperative that you call someone in the residential duct cleaning business or in HVAC maintenance to make the repair. If you are not sure whether you have separated duct work, or any of the other problems mentioned here, you are advised to consult with Air Duct Cleaner El Monte, who can answer any of your questions.