You may be doing all the proper air conditioning maintenance to keep your system maintained, but it will not matter if the duct work has not been cleaned and sealed. All of the cool air can escape from your air ducts, which causes your entire system to have poor airflow and wastes energy on air that never makes it to the intended rooms. That's why you want to verify that your HVAC system duct work is working properly. Here are two ways that you can increase airflow.
Clean Your Air Registers
All vents in your home have an air register that the air must flow through. Over time, it is possible for the registers to become filthy due to dust that has made its way through the system. All you need to do is remove those registers so that you can clean them.
Removing the air registers should be as simple as taking out some screws and removing the cover, but this can be problematic if registers have been painted over. You'll need to use a razor blade to cut around the edges of the vent cover where the paint has sealed it onto the wall.
Once the cover has been removed, clean the inside so that dust is no longer covering the vents. You can also clean the area around the vent opening, since there could be dust that will be blown right back into the clean vent cover.
Clean Your Air Ducts
It is possible that there could be clogs within your ductwork that you cannot see, due to dust that has collected deep within the duct work. You can fix this by scheduling a professional air duct cleaning. This will suck all of the dust out of the ductwork with a powerful vacuum, which will improve overall airflow throughout the entire system.
Change Your Air Filter
All air that passes through your HVAC system must travel through your air filter. Unfortunately, a clogged air filter will diminish the airflow throughout the entire system. Try taking the air filter out to see how filthy it is. It's entirely possible that the air filter is packed full of dust and is actually limiting how much air can pass through it. Simply replacing the air filter will increase your airflow.
If you tried these three things and the airflow still has not improved, contact a local HVAC technician to find out what could be wrong.