You can’t ignore weak airflow with your heating, ventilation and cooling (HVAC) system. It’s typically a sign of an underlying problem. When you turn on your air conditioner or furnace, you should feel the conditioned air coming out of the supply vents at a relatively fast speed. Weak airflow means the conditioned air is coming out of the vents slowly or potentially not at all.
#1) Closed or Blocked Vents
Closed or blocked vents is a common cause of weak airflow. There are two types of vents used in HVAC systems: supply and return. Supply vents, as the name suggests, will supply your home with conditioned air, whereas return vents will suck in air so that it can be conditioned. Both types of vents need to be open and unobstructed for proper airflow.
#2) Insufficient Return Vents
Speaking of vents, you may notice weak airflow if your air conditioner if your home doesn’t have a sufficient amount of return vents. Insufficient return vents will restrict the amount of air that reaches your air conditioner and furnace. The end result is weak airflow and poor cooling and heating.
#3) Blower Motor Failure
If the blower motor has failed, you can expect weak airflow. Located near the furnace or in a separate Air Handling Unit (AHU), the blower motor is responsible for blowing air into the ductwork. It turns a fan, and the fan circulates air into and throughout the ductwork. If the blower motor fails, the fan won’t turn, nor will air enter the ductwork.
#4) Leaking Air Ducts
Another common cause of weak airflow is leaking air ducts. Research shows that up to 30% of all conditioned air in a typical home or building is lost due to leaking air ducts. If your air ducts are leaking, it may manifest in the form of weak airflow and higher utility bills.
#5) Clogged Air Filter
If you notice weak airflow when running your air conditioner or furnace, check the air filter. A clogged air filter is a common cause of weak airflow. The air filter is located near the blower. If it’s clogged – meaning it contains a heavy concentration of particulate matter – it will interfere with the blower’s ability to push air into the ductwork.
#6) Closed Dampers
For a zoned HVAC system, closed dampers may cause weak airflow. Dampers are valves that are used to control the flow of air throughout the ductwork. They are a defining characteristic of zoned HVAC systems. When closed, though, dampers will redirect air to specific areas of your home, which may cause poor airflow in other areas.