Troubleshooting AC Rattling Noises

If you have an air conditioner, then you probably love the cold air that silently blows through your home. Air conditioners often provide peace and quiet in the home and allow you to keep your windows closed. However, if you start to hear a rattling sound coming from your vents that breaks the silence you normally enjoy, then this may indicate that there is a problem with your cooling system, especially if you also experience a reduction in cool air. There are several things that may be causing the problem, so keep reading to learn how you can investigate the issue.

Look At The Vents

In some cases, the rattling noises may simply be the baffles in the vents moving back and forth. The baffles are the metal pieces on the vent covers that help to direct and control airflow. To check to see if this is the issue, look for the screws on the vent where you hear the noise. Remove the screws, pull off the air vent, and turn on the AC. If the noise goes away, then it is likely that the metal directional control piece that moves the baffles is loose or one of the baffles itself may have come apart from the vent. Replace the vent cover to stop the problem.

If you need to replace your vent covers, then make sure to buy ones that allow for the greatest air flow through your home. This is wise if you notice a reduced amount of air coming through your vents in addition to the rattling noise. Look for covers that have the largest holes or openings. You can also purchase register-booster or vent fans for the rooms where you want to feel the most amount of cool air. These fans can be used in place of your regular vent covers, and they feature a fan that activates when your AC system turns on. Booster fans do need to be plugged in, so make sure there is an available outlet near each vent that you want to replace.

Investigate Your Ducts

If your issue is not as simple as a rattling vent, there may be an issue with loose ductwork. Ducts that come loose at the seams can rattle as air moves past. If an inexperienced individual installed the ducts or made a simple leak repair, then the seams may have been sealed improperly or poorly. If duct tape was used, then the glue on the back side of the tape likely melted away, and the tape fell off. This can also happen if foil HVAC tape is used to seal the seams. 

Inspect the ductwork in your home wherever it can be seen, like in your basement and attic. Look at all the seams to see if tape is peeling off or if there are any noticeable holes. Several pinholes can cause substantial leak issues and cause some rattling, so use a flashlight to closely inspect the ductwork. Also, jiggle the ducts with your hands around seams to see if they are secure. If you notice peeling tape, holes, or loose seams, then you should seal these areas.

Before you start repairing your ducts, makes sure all duct seams are fitted with sheet-metal screws around the circumference of each seam. If you do not see any screws, then you should add these first. You will need some sheet-metal, type A or type AB tapping screws. Use your drill and a small bit to place pilot holes in the ductwork. Place the holes about three to four inches apart around the diameter of the ductwork. Each hole should be placed about one-eighth to one-quarter of an inch in from the lip of the seam. 

Once the screws are secured, purchase a bucket of mastic. Mastic is a thick, white putty that will seal gaps and openings in the duct seams. You can use a paintbrush to apply the mastic, and you should spread the material thick around each seam that needs to be repaired. You should add a one-quarter to one-half inch thick layer of the material, and the mastic should be spread out about one to two inches on the right and left sides of the seam. 

For professional help with solving your rattling vent problems, contact a company like A Absolute Plumbing & Heating.


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