My High Efficiency Air Conditioner Is Making a Loud Noise

Vents

• Loose vents can rattle around as the high efficiency air conditioner operates, causing a clanging noise throughout the system. Ducts also create noise as they expand and contract with use, whether they’re metal or flexible. You can secure the ducts to a wall or support beam within the attic or crawlspace with duct tape or special duct straps.

Housing

• If a fan is improperly mounted onto the fan axle, it can scrape the sides of the fan housing, causing a loud noise and preventing the fan from blowing at its fullest capacity. The power to the unit should be turned off at the breaker before you inspect the inside. You can remove the fan-housing panel from the high efficiency unit to access the fan housing. Turn the fan manually to determine if it strikes the sides of the housing. If it does, the fan should be dismounted and remounted correctly onto the fan axle.

Trash

• Sometimes debris, such as a trash bag or a stick, can enter the fan housing through the intake grille. The trash can wrap around the fan axle or gum up the gears, causing a clanging noise. Not only is debris a noise causer, it can damage the fan motor as well if the fan motor is allowed to run while the fan component is hindered. For this reason, the electricity to the unit should be turned off immediately when a loud noise begins. After fan-housing panel removal, the fan housing area should be searched and cleared of all foreign objects.

Bearings

• When the fan’s ball bearings are running dry, they can cause a loud shrieking noise and hinder the fan’s performance. The ball bearings don’t glide as efficiently as they could inside the axle and could cause the fan to jam up, which prevents air from blowing fully into the home. You can remove the outside unit’s fan housing panel to access the fan component. Electric motor oil can be inserted into the ball bearing lubrication ports to lubricate the ball bearings. Turn the fan manually a few times to disperse the oil evenly amongst the bearings.