If you suspect that you have a problem with your ventilation, then you have a couple of options. You can try to diagnose the problem yourself or you can call a professional. It's a good idea to try both.

How to Diagnose a Ventilation Problem

Figuring out the exact nature of your vent problem is a lot easier than you might imagine. To start, just turn the central fan on and check each vent. You should be able to feel a light breeze from each vent. If you can't really tell a difference, then you'll need to check the heater and/or air conditioner.

Close every window and door and your house possible. Then, run the heater or air conditioner for an hour or two. At this point, you should check the temperature in every room that has a vent. You should be able to feel a noticeable difference in temperature if there is some sort of blockage in the ventilation. If you still can't feel a difference but suspect that there is a problem, try the HVAC system that you didn't try earlier (either the AC or heater). If you can feel a difference with the heater but not the AC or vice versa, then your ventilation system is probably clear. In such a case, you will likely need to take a closer look at your central heating and air conditioning appliances.

Once you have identified which rooms are getting air and which aren't, you can get a good idea of where the blockage is. If multiple rooms are affected, then there is likely a blockage deep in the ventilation system before it forks out into those rooms. Deep blockages are generally impossible for the average homeowner to reach without specialized equipment.

If only one room is affected, then you might get lucky and be able to remove the blockage on your own. Open up the vent coverage and see if you can spot the blockage with a flashlight. Even if you can't see it, try probing around with a long, thin object. If that fails, then you will likely need to call some help.

The Pros

Professional vent cleaning services can reach just about any blockage in your vents. They usually use a specialized vacuum with an extremely long hose, which can reach deep into your vents. On top of that, a professional visit for cleaning ducts can also result in much cleaner vents in general and less dust floating around.