The AC belt is probably the most simple component of a vehicle's AC system, but still a very important one. The belt connects the AC compressor clutch to the engine crankshaft, which allows the compressor to be turned via the engine's power when activated. As with most automotive belts, the AC belt will either be a V-belt or a serpentine. A serpentine belt is flat and ribbed, and serves to connect several components, while a V-belt is narrower, shaped like a V, and connects only two components. Whatever the case, when the AC belt fails, or begins to fail, it will display symptoms that will alert the driver that the belt needs to be replaced.
1. Squealing noises when AC is on
One of the most obvious signs that a belt needs to be replaced is that it will produce a loud squealing noise when the AC is turned on. In some cases, this may be attributed to a loose belt, or perhaps water or oil contamination. However, in other cases this may be attributed to a severely worn belt that can no longer properly grip the pulleys. When the belt can no longer grip the pulleys properly, it will slip under the torque of the engine and squeal. Often times this squeal will be very high pitched and noticeable. This is probably the most obvious sign that the AC belt requires attention.
2. Cracks in the AC belt
Another more visual symptom indicating that the AC belt needs to be replaced is that cracks will begin to form on the belt. The longer a belt has been in service, the more heat and wear it has been exposed to, which will eventually lead to dryness and cracking of the belt. An old belt will not grip properly and will actually be a lot more susceptible to breaking than a newer belt. If a belt is showing cracks then it should be replaced.
3. AC belt breaks
Another obvious sign that the AC belt needs to be replaced is the belt snapping. Old belts will snap simply because they are weakened by age and service. You can notice that a belt has snapped because the AC will not function when activated. A quick visual inspection of the belt should be able to identify if it has broken and needs to be replaced.
4. Inability to defrost windshield
Another less common symptom indicating that the AC belt needs to be replaced is the windshield defroster not working properly. The defrosters in some vehicles are connected to the air conditioning system and will require the AC compressor to function for the defroster to work. If the belt snaps or is slipping, then neither the AC compressor nor the defroster will work.
While the AC belt is a very simple component, it is very important to the operation of the AC system. If you suspect that you may be having a problem with the belt, or need to have your AC belt replaced, this is something that any professional technician, such as one from YourMechanic, should be able to take care of for you.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing AC Belt and was authored by Eduardo Ruelas.