A home heating and air conditioning unit makes several noises during its operation due to vibrations. Not all the vibrating noises signal a problem with the equipment or the need for a service technician. However, some noises do signal a problem. If you want to properly monitor your air conditioner, be sure to know the difference between a common noise and one that means your unit is in danger of breaking down. The difference is not always easy to notice, in some cases.
Rattling and Banging
One common vibration noise from the air conditioner and heating unit is the rattling, banging and clanking noise. This noise is not always a sign of a big problem. In some cases it is just a simple loose part inside the machine. The noise occurs when the fan blade spins around and strikes the loose part. A service technician is able to tighten or replace the part in a simple service call. Do not attempt to take the machine apart yourself, as this may prove dangerous and could cause more damage to the machine.
A clanking noise is another type of vibration sound emitted from an air conditioner. This noise occurs when a bent or broken fan blade strikes the grate or another part inside the unit. The fan blade rotates at a high speed, so this noise is frequent, fast and often sounds like a buzzing noise, especially when the machine is operating at full speed. A replacement fan blade usually solves the problem. This is an extensive repair but it is not serious. A bent fan blade does not signal another problem with the motor or compressor.
A hiss is another problem altogether. Hissing sounds accompanied by knocking, banging or clanking sounds, signal a problem with pressure inside the air conditioner compressor. This is a serious problem, as it could lead to damage to your motor, compressor and condenser. If you hear a hissing sound along with another vibrating noise, shut down the heater and air conditioner by closing the breaker switch labeled "AC" or "Heater" in your home's breaker box. Then call a technician to diagnose and repair the problem.
Common compressor noises come from vibrations associated with the operation of the compressor itself. If the compressor mounting bracket is loose, or broken a rattling vibration comes from the machine when the air conditioner starts cooling the air. Piston pins, connecting rods and shafts cause many common vibrating noises inside your unit. These sounds are dull, metallic vibration noises that occur regularly. If you hear these, a service call is the next step. Replace the parts to avoid potential, future damage or breakdowns to the machine.