Having weak air flow in your central heating and air conditioning system is not a good thing at all.
When you have this issue the first thing you should do is call your local heating and air conditioning company to have a look and see what the issue is.
Most of the time it is that you need your ductwork cleaned. This is the first thing the heating and air conditioning company will check. If it turns out that it is the ductwork that needs to be cleaned, the heat and a/c specialist will usually offer to do it right there on the spot as long as it isn’t a deep ductwork cleaning that is needed. In the event that a deep ductwork cleaning is needed the heating and air conditioning specialist will have you set up another heat and a/c home services appointment usually within a few days of the initial HVAC visit. In the event that it is a heating and air conditioning emergency and the ductwork deep clean needs to be done right away they will do it right on the spot but charge you quite a bit for emergency heat and a/c home services even though they are already there. This was what I heard from a friend of mine who needed emergency deep ductwork cleaning to unblock the air flow of their central heating and air conditioning system unit. I have been fortunate enough to never have this happen to me before because I am always having my ductwork cleaned on a semi regular basis. This is what I suggest you do as well.