Why is There No Airflow Out of Our Ducted Air Conditioning Vent?

If you’ve noticed a lack of airflow from your ducted air conditioning vents, it’s natural to be concerned about the efficiency and functionality of your cooling system.  Various factors, from blocked filters to issues with the ductwork, can hinder airflow and impact the overall performance of your air conditioner.  Understanding the common causes of this problem is essential to ensure your system operates optimally, providing consistent comfort throughout your home or office.  In this article, we’ll explore the potential reasons behind reduced airflow from your ducted air conditioning vents and how to address them effectively.

Why is There No Airflow Out of The Ducted Air Conditioning?

A duct has blown off.

Let’s look at how a ducted air conditioning system is set up to explain how this happens.

There is a central fan coil unit.  From this central point, the ducts run to the chosen rooms of the house.  They carry cold air in them, and the cool air comes out of the grilles installed in each room’s ceiling.  So, a system is designed with a central duct that branches into subsidiary branch ducts.  A branch take-off fitting diverts some air from the central duct into each branch duct.  One duct becomes two in places where it branches out.  The ducts are plugged into a Branch Takeoff Unit (BTO).

At the point where the ducts split, they become smaller in diameter.  This is needed to keep the air speeding up in the ducts.  If you move the air from one duct to two without reducing the diameters of the ducts, you’ll halve the amount of air going into those ducts, and you’ll lose airspeed.

It’s at the vulnerable BTO points that the ducts can blow off.  This can be caused by:

• Turning the air conditioner onto a high fan but with only one zone set to be functional can cause the system’s pressure to become too high in one duct, leading to the duct blowing off.
• When tradespeople work on your roof, they can damage the ducts by detaching them or causing tears.
• Poor installation means the ducts are vulnerable to detaching.

When a duct is blown off the BTO, large volumes of air are pumped straight into the roof instead of through the ducts into your rooms.

The zone controller is not working.

Some ducted air conditioning setups are zoned, enabling the user to have the airflow on or off simultaneously in different rooms.  When no air comes from any of the outlets and the system is turned on, it’s possible that the zone motor has died or is stuck in the shut position.  If so, you must call us to check the fault and potentially replace the zone controller.

A failed fan motor

Another common cause of air not coming out of an outlet is a failed fan motor.  To correctly identify the failure, a visual inspection and diagnosis are required. Once that’s done, we can assist with repair.

Still not getting any airflow through all vents?  Give us a call

So, what should you do if you have outlets that aren’t producing airflow?  Call PenAir, and we’ll send a qualified technician to service your air conditioning system.  We will perform a full inspection to check the reason for the fault and discuss how we can help get your aircon working efficiently again.