When your air conditioner makes any kind of noise it can be concerning. Noises typically signify some sort of issue with the function of your HVAC system. Different noises can occur for a variety of reasons. Whistling is one of these noises.


AC whistling noises typically signal an airflow issue. Think about when you whistle; you narrow the airway by puckering your lips and blow until you hear a high-pitched tone. Air flowing through your air ducts can work similarly. When there is high pressure and velocity flow, your air conditioner can start to make a whistling sound. This can also decrease the efficiency of your system and cause your energy bills to rise.


There are a few different aspects that can cause whistling. Some issues are easy to fix, while others can be more complex and expensive to repair.


Dirty Air Filters


When an air filter becomes clogged, it can block or restrict the air trying to flow throughout your HVAC system. The high-pressure air that does sneak through can cause a whistling sound. If your air filter is clogged, be sure to change it.


The standard 1” filter should be replaced monthly. Some high-efficiency filters can last longer, but it is beneficial to briefly inspect every filter on a monthly basis anyway.


Furniture Blocking the Air Vents


Furniture is another culprit that can reduce airflow. If you have any couches, chairs, tables, or shelves by your vents or return air ducts it can narrow the path for conditioned air to flow out of the vents and into your home. Be sure to keep the area around your vents and air ducts clear.


Too Many Closed Dampers


Dampers are a useful way to help direct air where you want it to go. If you have vents in an unused room, you can close the damper so that the cool air goes to the rooms you are using. This can help save energy.


However, if you have too many dampers closed, it can affect the function of your HVAC system. When too many dampers are closed, they are fewer pathways for conditioned air to travel. If the pressure builds up, it can cause a whistling noise in the places where the air is escaping.


Some dampers can accidentally close while cleaning your home. If you hear an AC whistling noise, try inspecting all of the vents in your home and make sure most of the dampers are open.


Too Many Closed Doors


Having too many doors closed can also restrict airflow throughout your home. While it can help to close off 1 or 2 doors to unused rooms, closing too many can put a strain on your air conditioner.  If you have too many doors closed, open them up to let the air flow.


Not Enough Return Inlets or Return Inlets That Are Too Small


Designing ductwork for a home can take quite a bit of science and engineering. The return and supply airflow needs to be balanced with the capacity of the blower. When these two aspects are not balanced properly, your HVAC system will begin to experience issues. If you believe that too few return inlets are the cause of the whistling, be sure to hire a professional like B&L Ott as only they have the knowledge and experience to ensure your system is functioning properly.


Leaky, Dirty, or Damaged Air Ducts


Similar to having your ducts designed incorrectly, having leaky, dirty, or damaged ducts can also hinder the function and efficiency of your HVAC system. For instance, if the seal where the individual pieces of your air ducts come together deteriorates, air can start to leak through and cause AC whistling noises. This is also an issue that should be inspected and handled by a licensed contractor like B&L Ott.


Bearings or Belts


It can be easy to mistake the type of noise your air conditioner makes. Screeching, squealing, and whistling can sound very similar. If the noise you hear is more of a screeching or squealing sound, it could be the belt on your blower or the bearings in the motor of your condenser fan.


When the issue is the bearings or belts, you can usually hear noise coming from your indoor or outdoor unit. It could also mean that your blower or condenser may completely fail soon. Be sure to schedule an inspection/repair with B&L Ott as soon as possible.


Refrigerant Leak


Refrigerant leaks can also cause a hissing or whistling sound. This is due to increased pressure inside your compressor. This type of issue can be dangerous, so it is crucial that this problem gets taken care of by a professional as soon as possible. The problem will likely worsen and cause other problems with your system if left unchecked for too long. You should also turn off your air conditioner if you suspect a leak.


Oversized HVAC Unit


If you have a large air conditioner that produces too much cool air for the air ducts to handle, the high pressure and velocity of air trying to flow through the ducts can cause a whistling noise. This can be one of the most complex issues that cause AC whistling noises. This is definitely a project that requires a professional like B&L Ott in Reading, PA. They will work with you to find the best solution for your home and HVAC system.


Give B&L Ott a Whistle


If your air conditioner is making noise and you can’t figure out why, give B&L Ott a whistle. We will send out one of our knowledgeable HVAC technicians to diagnose and repair the problem. A whistling HVAC system can be annoying, but the good news is that it signals a problem before it grows worse. It allows you to repair the problem before it causes a total system breakdown. We will help you solve whatever issue your system may be experiencing so that your family can be cool and comfortable this summer.