It's a hot Summer afternoon and you're sleeping in your comfy bedroom with an Air Conditioner providing soothing cooling. Suddenly, it starts acting odd and here what it does;
A whistling sound begins to come from the vents. Oh nooo!!!
Since you and no one likes his dreams to be disrupted by whistling sounds, whatever you ought to do has to be done urgently. But before you set up the venture of fixing the problem, explore the causes of such sounds:


Reasons behind AC making whistling sounds:
The major reason behind your whistling Air Conditioner is insufficient air flow through the return vents. And what causes the reduction in the return air flow? It could be due to:
  • Closed dampers
  • Blocked Return Vents
  • Several Closed Doors
and most importantly;
  • Dirty Air Filters

All these issues can be fixed right away with little effort and without calling a professional. But before we move on to the solutions, let us learn how does a low airflow cause whistling sound.

Here's how your vents whistle
Remember the whistling you learned in childhood? For that, you had to make a very small opening with your lips and blow air outwardly with high velocity. And the sound came out was of?  A WHISTLE! The same happens with your Air Conditioner. Your blower is operating all the time circulating air throughout the home. When there's insufficient air provided, the blower blows it with the same velocity and pressure. As this high pressurised air reaches the supply vents openings, it makes the whistling sound.

Fix your whistling Air Conditioner, do this
Close Dampers - Fix it
Dampers are valves that are located in your ductwork and are used to prevent air flow from reaching certain parts of the home. Locate your damper near the supply vents and make sure it is aligned sufficiently to allow proper air flow.

Blocked Return Vents - Fix it
What most homeowners do in order to not compromise on their interior is that they hide the return vents using furniture, carpets or other such blockages. This is such a grave mistake that it can affect the whole HVAC system. Insufficient air reaches the system and consequently, the system gets disturbed. If your system is making whistling sounds and you know you've done this mistake too, fix it by removing the blockages on the return air ducts.

Several Closed Doors - Fix it
Why that privacy? You can keep the doors open man! When the airflow comes from the supply vents of the main hallway or stairway and wants to spread in the entire home, it has to sneak from the small gaps under the doors in order to enter the rooms where the doors are closed. And what happens next? Insufficient air reaches there. As a consequence, insufficient air goes back from the return vents that then causes the whistling sound. To solve this, keep the doors open unless it's a super secret plan you're making inside. (Or at least keep them half opened)

Dirty Filters - Fix it
Although the most common reason behind the whistling sounds is dirty filters, we've mentioned it on the very last. And it is no additional information since you already know how important it is to clean the filters regularly. Clean them right away if the last time you cleaned them is the time you don't even remember.

Bottom Line
With home comfort heating and cooling appliances, you'll have to face issues every now and then. Although not all of them can be solved as DIY’s, there are many that can be. The above mentioned four solutions are what you can try yourself the next time your AC makes freakish noises.

Did that help? If yes, do let us know.

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