A shaking, vibrating air conditioning unit is loud and annoying. Over time, that shaking can also damage components in the unit. Fortunately, most vibration issues are easily repaired once you know the cause.
1. Loose Housing
One of the most likely causes of shaking and vibrating is that the housing that covers the outdoor unit isn't properly secured. Over time, the screws that hold it in place can work loose, particularly after winter temperature fluctuations. The cause could also be that the screws weren't properly tightened after the last time the housing was removed for servicing. Fortunately, this issue is easy to fix with a screwdriver and a few minutes of your time.
2. Fan Imbalance
The fan inside the AC unit should run smoothly with minimal vibrations, unless, of course, it is not balanced correctly. A fan may become imbalanced because there is dirt on the blades or something tangled in the blades. Poor lubrication can also lead to imbalance. A cleaning and lube will solve the problem. In some cases, a fan is imbalanced due to damage, such as a broken blade. In this case, the fan may need to be replaced.
3. Worn Bearings
Bearings inside the fan assembly help ensure that fan motor rotates the fan smoothly and without shaking. Over time, bearings can wear out and the fan may begin to run a little rougher. Bearing issues are often accompanied by squealing noises along with the excessive vibrations. You can have the bearings repacked and lubricated, which should fix the problem.
4. Broken Motor Mounts
The fan motor is mounted securely to the inside of the unit so that it doesn't move or shake. Over time, the motor mounts may become loose or components on them may even break. Fortunately, if you catch the issue early you can have the broken mount repaired or replaced. Ignoring the issue can cause damage to the motor due to the shaking and vibrations that occur while it is loose.
5. Pad Issues
Your AC should be installed on top of a concrete pad, and there should be anti-vibration pads placed between the unit and the concrete. This is because all AC units do vibrate slightly during operation, but the pads should absorb the vibrations. If the pads are missing or placed incorrectly, then you will need to have them replaced in order to stop the shaking problems.
Contact an air conditioning repair technician immediately if you notice that your unit is shaking or vibrating violently.
